You say you do it constantly but it doesn't bother you. Do you also do it when you feel happy or relaxed?
because in my mind, rocking equals being stressed/anxious. I'm just super easily stressed and I have a hard time finding out what exactly is making me stressed most of the time.
I rock side to side when standing (if I don't I feel like I'll fall over!) And front to back or side to side when listening to music. When I'm sitting, sometimes I rock or jiggle my leg.
It's my default state. Always has been. If you ever catch me NOT rocking I'm either unusually relaxed, or nearing shutdown. 80% of the time I'm rocking or moving.