for the past few times ive been trying to make something, the fill bucket either doesn't work, or it only fills part of it.ive tried a lot of things but it still doesn't work.

Yes, it has to do with how the vector editor handles lines. The Scratch Team is working to redesign this – so stay tuned for improvements!

In the meantime, you can try drawing using shapes instead of lines, and then using the reshape tool to change the shape the way you want it. The reshape tool is the second tool on the paint editor (above the pencil tool).