Lindsaymarie,
I totally agree with Grinity. As a student, a professor and more recently Mom and elementary teacher, gumption is hands down the trait that I look for. This is your education and you need to be your own advocate. Go to the head of the department, or, indeed, the principal with a plan. Perhaps it's independent study or perhaps it's an outside mentorship or perhaps it's attending a seminar at a local university, but it is something that YOU want to do. One often hears that "it can't be done" because there is no formal reciprocity between institutions. That is simply ridiculous: a teacher at your HS can sponsor an independent study while you officially audit a university seminar but actually do do the work. Most professors are thrilled by the idea that someone really wants to take their class and will work with you.
Keep me posted!