Hi Laura:
I'm 42 and I hated school as well. I had to deal with people who thought I was ret*d and, because of my learning disabilities, I couldn't prove them wrong. The only good thing about the whole experience is that I survived it and emerged, like Phoenix, from the ashes.
If I were you, I'd talk to your Mom about enrolling in a private school or doing home schooling. Private schools tend to have smaller classes and the teachers tend to be higher caliber as well, so they can--and do--spend more time with each student. The biggest advantage to home schooling is that if there's a subject your Mom can't teach you about, she can bring in a tutor and/or you can get tutoring on-line. (I've often wondered why, with the advent of the Web, we hear so much about online college degrees but so little about online high school diplomas.)
If your Mom insists on you staying in school (I presume it is a public school) then the bad news is, you may have to grin and bear it. My advice then would be to find other students like yourself and befriend them. Join a club, like Chess or Physics or Drama. And--whatever you do--never, ever go to a pep rally. Cut out of school early, go to the library, do what you have to do to avoid those wastes of time promoted as "showing school spirit." It's BS. But then, a lot of stuff at school (and life) is BS.
Good luck to you. Please let us know how it works out.