I say for the time being don't worry about her going away...as you don't really know what the future holds for both of you. Work on what relationship there is there right now, build on that, and worry about school when it's appropriate to worry about. If you really feel that you want to have a relationship with her then work on that.
I say give her a call, make plans. Don't ask her on a date, ask her if she wants to go do something. Make sure it's something that you know you will both have fun doing. If she has any sort of feelings towards you now, having a good time with her and making her happy and having fun will only help that.
Then, pee in her butt.