I twitch when I think of self harm...?

I've been self harming since I was around 10 and I'm now 14 but in the last 2 years, I had gotten a lot worse, I started to cut deeper and more often and since this, I've developed a sort of twitch, when I think of self harm, my neck just snaps to the side and I almost curl up into myself. I can keep it under control for the most part but sometimes I really can't and it's clearly obvious to others. I also start digging my nails into the back of my neck or sometimes I'll start throwing my hands around, bending them, twisting them, anything that's painful and keeps my hands away from the rest of me. I just get so frustrated, so easily and I used to think of self harm in a "normal" manner, just thinking of the act itself and wanting to do it, I don't anymore. I get these flashes in my head, digging nails and screws into my skin, throwing myself against windows, breaking bones, burning myself, it gets a lot worse than that, I actually have flashes of me screaming out in pain, it gets REALLY twisted sometimes, it's horrible and I really feel I can't control them, these are often followed by or before the twitch. I know I should go to a counsellor and I fully intend on doing so soon, I just have to work up the courage to tell my parents that I don't think I'm better yet (I went to a counsellor about a year ago when my parents found out that I self harm but my parents didn't trust her and pulled me out of it.). Since I've just gotten a lot better at hiding things, although, I haven't cut in a few months now, I'm trying to get control over myself but it still doesn't stop the thoughts and the twitch. I guess I just want to know if anyone has a similar habit? I'm just trying to find out if this is common in self harmers. Thanks.