I'm going to break my leg so I can get crutches.
Why would you want to break your own leg?
I want to have more attention and sympathy at school
To abuse yourself just for attention and sympathy is sick behavior. You need to get some immediate therapy for what is obviously a serious depression problem. You also suffer from self esteem issues.
It's no big deal.
Sure it is! Your practicing self harm for the sake of attention. If you break any limbs, you could be permanently disfigured or worse.