Write Away

What does she want? What is preventing her from getting it? How will she overcome those obstacles?

Those are the three basic questions that drive Plot. Once you figure the answers to them out, you've got a framework to hang your story on. Then you can get into the motivations of the people around her--for example, is her mother afraid she'll get hurt on the sharp edges of the world, or embarrassed that her daughter isn't neurotypical, and that's why she doesn't let her go out? Some amalgam of both? Something else altogether?

When I'm stuck, I look at my characters and ask questions. Frequently I do this with a pen and paper, the old-fashioned way. I also break the plot down into the seven-point structure to keep myself on track with what needs to happen when.

I hope that helped somewhat. :)