I'm depressed and I don't know what to do?

It sounds like you are still in your early teens...and that is a common age to feel totally out of whack...with everything in your life....been there :). I would suggest finding someone you trust (friend, mother, etc ) to talk to at least to vent...and then if you think your fat start excersizing..thats one of the first things a doctor would tell you anyway...and it really does increase your moods. Also, can you go to a counselor at your school?