I think I'm bi-polar?!

Mood swings in a bi-polar person don't usually shift so extremely in a matter of hours. However, a lot of what you are saying is consistent with the disease and you should probably get it checked out. I would start with a conselor at school--these people are paid for this sort of stuff and they can get the ball rolling by helping you talk to your parents and getting you medical attention if you need it for medication. If that is not an option, you can always try local shelters. A lot of them offer mental health counseling, but because you are a minor, you will still need your parents' permission to receive any kind of medication. I know your suffering all too well--I didn't get any help until I was almost 22. Good luck.

Whilst it may just be your mood swings are more violent that others, it may indeed be that you are bi-polar. If you are worried visit a doctor and ask them for advice, legally they have to keep it confidential so no-one else will have to know.