You're not rambling, I understand you perfectly.
When I do (did) it, I seem to lose contact with my surroundings almost - all I see and focus on is what I am doing and waiting for "it" to appear.
I had 19 at one time, my pants used to rub on them while I walked and made it hurt more - I enjoyed knowing that I had caused that to happen (stupid, huh?)
I once held something up to my throat and made a few cuts - when I snapped out of it (a back-up generator coming on startled me) I was horrified to see what I was holding and what I had been doing. Scared me big time. I kept thinking what if.................... So, yes I understand about the trance thing.
You're doing it because you have problems that need to be worked out - feelings that are being suppressed and have to be acknowledged. I'm not a shrink, but I have way too much experience in this area not to have some of what my T tells me rub off onto me.
You have two choices (or at least I did): 1. you can figure out what is wrong and deal with it - express the emotion and work thru it, or 2. you can suppress it all and shut down emotionally.
Unfortunately (?) I have chosen #2 simply because it is easier for me and I function better this way. It isn't the right way though.
Please take care of yourself and pick #1, okay?
Mary Alice