It's hard when your parents are unsupportive and invalidating. I'm sorry it's tough for you right now. Please don't cut yourself....I promise you will come to regret it! The scars I have from cutting leave nothing but shame and the relief cutting provides is temporary. Could you work out some kind of contract with your parents...like they list their expectations and consequences and you list your expectations and ability to regain lost privileges when the expectations are met so you guys can find common ground? Sometimes putting it in writing takes some of the emotion out of the situation and allows you to understand each other better.
Is there a school counselor you can meet with? I'm sorry your parents aren't more understanding. I think Sannah has a good idea, when she gives you the link, let your dad read it or maybe I can try to find some information on the topic. If I find it, I'll post it for you. Hang in there! You are doing the right thing in reaching out, Welcome to PC