disclaimer: don't follow any of this advice if you don't think it's good (i'm in a vengeful mood because sexual harassment and bullying were mentioned)
talk to a school counselor about being tripped, being called obscene things, and being sexually harassed by groping. if they don't take you seriously, or tell you it's your own fault for dressing like you do (some would be idiotic enough to say something like that. better be prepared for it), tell someone else. record the conversations for later use, just in case your school is run by idiots. if everybody else fails to do anything about your situation, talk to the principal. the next step would be to report every single person who's groped you and the adults who failed to intervene.
when you have told someone (best to tell more than one) about it and asked for help, you can use moderate amounts of violence if it's needed to defend yourself. boys often do that. don't try it before asking for help though, the other kids will just say that you started it. you could also yell at people if violence isn't your thing, just be careful not to call them obscene things ("rapist" would be a fair thing to call a harasser though). attack them, not yourself. (i'm not promoting violence, really. just naming an option, as i'd break the fingers of anyone who tried to grope me against my will. it's their own fault).
it's not that bad if you get expelled from a place you would've dropped out of anyway if things don't get better, there's nothing much to be afraid of from the adults. but you still might want to try getting some support from the school and help from a counselor or therapist while it's still possible to fix things.
just one thing. when people wrong you, respond with rage. the other kids won't like you more for doing that, but it does help you stop the self blaming. it feels really good to kick the foot that was placed in front of mine. much better than being tripped and start crying because the world is so unfair (i've tried both). i also think there is something weird about bullies, that they don't stop unless they're opposed seriously. it's fun to bully someone who starts crying and is too afraid to tell anyone about it. it's not as fun to bully someone who responds with an angry "f** you, that hurts, you d** b***!" and looks at whoever it is like they were the worst scum of the earth. it won't gain you more friends, but could make your time in school a little more peaceful.