This is very common. It's called head banging and is more common in highly strung children, and intelligent ones too but also autism etc. My friend's little boy does it and also "rocks" from leg to leg when he's anxious. My husband still rocks when sitting for comfort and I wiggle my foot when going to sleep. Adult forms of it I reckon.
It will not have affected you one bit. Shaken babies are abused with significant force and it is before they have developed good neck muscles so the affects are worse.
Sounds like you come from a head banging family tree. My sister did it a lot (against a wall, but then she is severely intellectually disabled, not from the head banging) and the neighbours once plucked up the courage to ask what the bang bang bang in the middle of the night was. It was embarasssing to tell them but I hate to think what they thought was going on.
Good luck.
Well perhaps Mom could have suggested you not do it so hard, but thats past anyway,I dont know how old you are now, but I suggest you are okay if you feel okay, if you get headaches or anything you feel related to this, go visit your Doc and ask him what he thinks.and he will see if you need evaluating further.Maybe you are thinking about the past a lot and some things once we hear about them can make us anxious,