First of all, thanks for sharing!

I can relate in a way since I have self-harm fantasies, especially when I'm stressed. Pain is a fascinating thing. To have a sensation so intense that it blocks out all others, to experiment with different kinds of pain... I think it's beautiful. BUT I'm afraid it is not normal and most people are creeped out by this. If it is a symptom of a specific something, I don't know.
I used to self harm frequently in the past but when I started practicing martial arts I found a way to satisfy the desire for pain without actually injuring myself. It is a great relief to actually live it out without feeling abnormal. If you're not already into MA, I strongly recommend it.