The sooner you get help, the better off you'll be. The worse your OCD gets, the harder it will be to get control of it (but never impossible). Have your parents seen what you've gone through all these years? Or have you hidden it from them? It amazes me that people can watch a person go through OCD for years and still think they're pretending.

If you have to, try calling a psychologist from the phone book, or even call a local high school and ask to talk to a school counselor and tell them you need help, but your parents don't believe you. Maybe they can help.