How can I stay motivated in school?

Well, you could aim for Yale -- a great New England university with an outstanding drama department. You could use NYU and Var as backups, also with strong drama departments (don't know how strong Var is in science, though). Carnegie Mellon is another school that's strong in both the sciences and in drama. A school that is good in sciences AND drama would give you a chance to scratch that acting itch, while still aiming for a science career. Perhaps if the acting instructors at Yale or NYU lauded your talent, your family would reconsider their stance.