How to deal with overprotective parents?

I'm 13 and my curfew is 8pm and my bedtime is 9pm (9:15pm weekends) and I cannot use anything electronic after 8pm. I cannot have my own computer because "they need to supervise me for not going on websites not suitable for child's eyes". I already have a computer time limit that limits my entire computer time to 2 hours (1,5 hours weekends). Every time there's even a bleeped curse word on tv, they say "don't listen! This is not suitable for children!" and change the channel. If there's even a little bit of violence in a video game, I'm not allowed to play it even though its rating lets me play it! This overprotectiveness has lead to bullying and it makes me cry every night as I get called "The gay sissy" and other names. I self-harm because of this (not cutting myself, but banging my head to a wall and such), and every time I even bang my head into a wall I get grounded for a day! How can I make them believe I've grown up since I was something like 9 and am a teenager now!?