Do you have a therapist? Or someone nuetral that you can talk to about these things? Head-banging is a no no it could do so much damage. I can relate as well. Although my SI isn't so much about punishment anymore, at it's early stage that was very much what it was about. And also I've found that when I reached that stage the severity of the SI increased because it didn't seem like enough.

Feel free to pm me anytime as well. I'm not about all, all the time but if I get a pm I always respond *even if it's not right off* Take care of yourself. And welcome to PC