I'm sorry you are going through this. It's so hard to not have answers and not understand what is going on in your child's mind, especially when the behavior is so out of the norm.
I'm glad you're getting help. If your psychologist/ psychiatrist doesn't seem to know, maybe get a second on board, too.
Mostly I just wanted to write and say that I don't think you need to lock your self in your room at night and I it is an awful conculsion to jump through that your child might be ready to harm people. He has some issues, sure, and they are different than the normal teenage stuff. I would certainly exhaust all resources available ASAP as he is at an age where the brain chemistry changes considerably and intervention, if necessary, should be sought before patterns are formed. There are many things that can develop with puberty (for me, I started showing signs of narcolepsy -- I randomly fall asleep -- and it's just one of the things that take that long in life to develop) but with treatment can be controlled.
Also, it might be embarrassing or frightening for him. Surely he notices he's different or can't stop himself from doing these things and maybe that lack of control is hard for him to deal with. With therapy, perhaps he can learn to control these urges and modify his behaviors.
We're not equipped to give you advice on this one. I'm just sending you a hug and keeping you in my thoughts.
Best of luck to you.