How can I get out of my academic situation?

Today I learned that on my final report card I will be getting a D in my math class, a class in which I have received A's in my whole life. It was because I failed 2 tests and we've only got 3 grades in the system, all tests. The last test I got a B. What should I do? Ive been in the class for a whole semester and I can switch to the regular class, Im in honors, but I don't know if i should. Also, I really hate the school system, I rather take college classes at college campuses. At least they give me credit. How can I do that? And do i have to at least take some classes at a regular high school because i might be a semi-bright student but I really don't like the curriculum of schedule of school.