This is a excerpt from a story I've written. Hope you enjoy reading it & find it satisfactory. <3

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She came in the night, like she always did.
I watched her shadowy figure glide silently across the hallway, so precise and lightweight. How beautiful she was!
I couldn’t help marvelling at how graceful her movements were. She didn’t just walk, she flowed. Like a flower opening to the rain, a little miracle, a beautiful ghost-like woman walking with such grace across my hallway.
She was a mystery, I had no idea where she came from or why she was in my house. She was just there, no identity, except for the ones I made up for her. Every night she came. And every night I watched her.
My eyes followed her, fascinated, as she passed my line of sight then disappeared around the corner.
I then lay down, hugging my pillow to my chest, and wondered, as I had every time after seeing her, who she was and where she came from.
She was so strange, and I had thought and thought of her so much that I half believed it was actually a dream, one that I returned to every night. But deep inside, I knew I could never have imagined such a detailed figure, nor such grace.
I hadn’t told anyone about her. No one would believe me, anyway. They’d all think I was crazy. But also, I didn’t really want anyone to know. She was my secret, and I didn’t want to share my secret with anyone.
But I didn’t exactly know who she was either. And I resisted the temptation to find out.
What if I didn’t like who she was? What if I didn’t want to know? What if she was a hallucination my overactive mind had created? I was safe as long as I believed in my illusions.
I sighed aloud. I should go to sleep now.
But something kept me awake, a sort of instinct, the kind that you feel before adventure, when your mind is so occupied that sleep is out of the question. So I lay awake.

★

My name is Grace Ennest. I’m 11 years old. I live in London. And ghosts haunt me at night.
It was kind of ridiculous if I was being honest. Like, literally, a ghost walked across my hallway every night and I pretended to the world that she didn't exist.
It’s been happening for over two weeks now. The first time it happened I had run to the door and stared at her with my eyes wide open, sure that I was dreaming. She had appeared like an apparition, without making even the slightest sound and she walked like one too. She didn’t see me.
It was a dream, I had told myself. Just a dream.
But then it happened the next day, and the next. And I came to accept that it was real.
Every night I eagerly awaited her arrival then drifted into an uneasy sleep after she left. It was all so mystifying.
What was she doing in my house? Why did she come here? Why did I watch her?

I let out a sigh. Thinking about all this was pointless. There was a ghost in my house. That was it. End of discussion. I needed to get on with my life.
Oh, what was the point? I couldn’t seem to stop thinking about her so I gave up my futile efforts.
Feeling suddenly thirsty, I decided to go downstairs to drink some water. Swinging my feet off my bed, I slipped on my fluffy white bunny slippers and made my way down the stairs.
It was so quiet. In the daytime the house was so noisy. You could always hear the TV blaring the news, my older sister Alice talking nonstop, Dad yelling when he lost the car keys. Now it was so odd when the only sound was the soft thump of my feet against the carpeted stairs.
I knew I was being ridiculous, but the intimidating silence and my thoughts about ghosts had left me quite anxious. I gripped the handrailing tightly and dragged myself down, step by step. Switching on the light, I ran into the kitchen, quickly grabbed my cup and poured some water into it, accidentally sloshing some against my nightgown. Oh well. It’ll dry.

After my little adventure on the stairs, I found that I wasn’t very thirsty after all, and only drank a few sips. Setting my cup down, I switched off the light and had already set my foot on the first step to go back upstairs when I noticed that the light in the living room was on.
I frowned. Maybe Alice had been here and had forgotten to turn it off. That seemed like something she would do.
Thinking about how forgetful my sister was, I absentmindedly walked over to the light switch. I wondered if perhaps she had left the fan on as well. I had already taken a step to go and check when I froze, an audible gasp escaping me.

★

She was there.
I clamped my hands over my mouth, wondering if she had heard me.
I couldn’t believe it. Of course, she had walked through my hallway. She must’ve come down the stairs as well. I had spent so much time wondering who she was, I had never thought about what she did in my house.
She hadn’t noticed me. She was standing at the window, leaning slightly out, watching the starry sky outside. Her long dress flowed down, blowing slightly from the wind.
Up close, she didn’t look like a ghost. Her skin was most definitely not transparent. She looked like a normal person, except normal people don’t mysteriously trespass into others’ houses.
She was clearly in deep concentration, the reason she hadn’t seen me.
As I watched she suddenly began to sing in a beautiful, clear voice :

Where the crystal clear water
Flows down to the sea
Where sky and where ocean
Always shall be
Where sweet is the nightingale’s song
As she calls out to me

I listened, enraptured. The fact that she could sing, that she had a voice, it seemed to make her so much real.
Who are you? I wondered. Where do you come from? What are you doing here? What is the song about? … I’ve never heard it.
I had a thousand questions, but I was afraid to ask them. How would she react to me?
Before I could make a decision, suddenly, with a sigh, she turned around. Her eyes widened as they met mine. Her hands gripped the windowpane and she backed up in shock, even though there wasn’t anywhere else to go.
“Wait!” I said automatically, stepping forward, wincing at how stupid I sounded. What was I asking her to wait for?
Her eyes scanned my face. Finally, deciding that I posed no threat, her body seemed to relax.
She opened her mouth to say something, but before she could, a figure rushed past me, brushing my arm, and went to stand beside her.
“Ariana! What are doing here? I want to show you something!”
The figure was a girl - around my age, maybe a year or two younger. She had dark auburn hair, and bright, hazel eyes.
She waited for a few seconds, then seemed to realize that something else was going on here. She turned around slowly, and her eyes fixed on mine.
They brightened.
I could tell that this girl had a very bubbly personality, that she was the sort of person who loved meeting new people and getting to know them. And in this case, that happened to be me.
“Hi,” she said. “Do you live here?”
“Yes,” I answered slowly, still trying to get over my initial shock.
“I’m Clara.” She bounded forward, her hand extended. “And this is Ariana. Don’t mind her, she’s just thinking too much. That makes her seem cold, but she isn’t actually. What’s your name?”
I stared. The girl was very talkative, but there was something in her friendly smile that made me instantly like her.
“Grace,” I said, shaking her hand with a smile of my own, and feeling quite odd.
“Well, Grace, it’s a pleasure to meet you,” said Clara, grinning.
“Nice to meet you too,” I said solemnly.
The ghost - Ariana - stepped forward, her lovely face as expressionless as I had ever seen it.
“I know you must be wondering who we are and why we’re in your house. I can explain, in time. But you need to understand first. I’m Ariana.”
I nodded, not sure what she meant.
“I’m sorry for all this -” she began.
“No, don’t be,” I said, finding my voice.
She gave me a faint smile. I returned it, thinking about how quickly my life had changed in just a few minutes.

★

And so I made the acquaintance of Clara and Ariana. I was in a sort of reverie by now, not sure whether I was dreaming or not. So when the other children came running in, I felt like someone had poured a bucket of freezing water on my head. I woke up, in that way you suddenly wake up from a daydream, realizing that everything you ever dreamed of was right in front of your eyes.
I pinched myself hard several times, but I couldn’t seem to wake up, so I decided that it was real after all.
There was something remarkable about those children that I couldn’t place. They all had an aura of strange beauty about them, but, no, that wasn’t it. They seemed so - joyful. Unburdened by everything that troubled the children of today.
They came up to me one by one to introduce themselves, and I started to feel very awkward.
Joyce. Freddy. Victor. Rosalie. And Lily. Those were their names.
Lily was the youngest, perhaps about 6 years old. She walked up to me shyly, tucking her brown hair behind her ears.
“My name is Lily,” she said in a clear, sweet voice.
“And my name is Grace,” I told her.
She gave me a smile, and I couldn’t help but return it.
“Grace!” Clara called, coming forward, and taking me by my hand. “We want to show you something.”
I led her guide me upstairs, the trail of children following close behind. The same staircase which had seemed so frightening and lonely during my descent down now seemed to be lit with a warm light, illuminating all that was to be seen.

★

The children were noisy, talking in loud voices and thumping on the stairs. I wondered what would happen if my parents woke up to see me in such strange company, then quickly decided to not entertain that notion. That’s something that I’d rather not happen. How on earth am I supposed to explain all this to them?
Clara stopped in front of the balcony, and releasing my hand, slid the door open. They all rushed forward to stand leaning against it, clambering to get to the front.
I let the wind blow through my hair, taking a deep breath and letting my mixed emotions run through me.
It was a moonless night, and the stars traced constellations in the sky. I recognized my favourites : the Great Bear, Orion, Cassieopia, the ones people had named so many years ago, people who had lived lives so different from mine, seen things I could only dream of seeing. If only …
“Look!” Joyce’s voice shook me out of my reverie. I turned to see where she was pointing.
Standing with her body braced against the balcony, Joyce’s arm reached up to point at something in the heavens above : an arc of light that shot through the starry sky with remarkable speed.
A chorus of oohs and ahs sounded as everyone watched the shooting star disappear around the corner.
“Beautiful, isn’t it?” Rosalie asked me, her golden blonde hair blowing in the cool July wind.
“Yes, it is,” I agreed. “I’ve never seen a shooting star before.”

That's a great story! I love the description and the interaction between characters. The only thing I would consider is showing a little bit more emotion in Grace. You're describing her actions very well, but I think it would make the story even better if you exaggerated the emotions, if you know what I mean.