I would just ask your parents why high school means you can't properly care for a bunny? You can feed her before you go to school and when you get home, and just let her out to run while you do homework. I honestly feel like there is never an "easy" time to care for a rabbit, so I think it could be a good lesson for you to learn to juggle two things.
Maybe ask your parents to have a "trial" for the first semester. See if you can care for a rabbit and do well in school for a semester. If you can, keep Milly. If you can't, then look for a rescue where she can get cared for as she needs.
At least worth a shot!