Everybody is different and unique. What you have stated are very similar, and yet your feelings and thoughts inside, the circumstances you live in, might be completely different. Slappy, Sara, there are dozens of reasons why a person may self-mutilate, and any one victim may have been reacting to several of these. I am evil and wicked and must punish myself. My world is a blank, I feel nothing.
Pain is better than emptiness.
The world is full of things I am terrified of. Physical pain distracts me from them, while I hurt I can focus on myself instead of all the nastiness out there. I might as well not exist. Nobody pays me any attention, unless I cause trouble. It's better to be punished than to be ignored.