I pick at my nail beds and cuticles, my nail polish, or grab whatever thing is in my peripherals that looks fiddle-able (she has silly putty and stress balls but I always go for the piece of string hanging off my pants!? They're probably covered in child mucus anyway). In the summer when I wore shorts, I would fret the skin on my thighs and make scratches without even realizing it. T did, however, notice the behavior and asked me to stop. It's anxiety related for me and the compulsion to do something hand-focused. I'm also very "tic-y" and bouncy when I'm stressed out.

Your scratching sounds normal, given your predisposition to sh. You could ask your therapist if she has any fidgets ie. tactile porcupine balls, silly putty, play-doh, whatever. Something to distract your hands from self-destructive behaviors. Next time you find yourself doing it, bring it to her attention. It certainly won't hurt to discuss it.