I'm experiencing the same problem with hunching over my knitting. I am trying to relax and sit up straight, legs out propped on the coffee table...it's helping somewhat. Just need to train the muscles, I guess!
Related to the hunching problem--and likely partly the cause--is I don't know what to do with the left needle. I can't tell from Amy's videos where she holds her left needle; I assume she, and most of you, hold the left needle up at a slight angle.
Yet, I cannot seem to knit without propping the left needle on my thigh, which means I knit at an awfully awkward angle sometimes. The result is a horrible cramp in my left shoulder that just will not go away! I'm sure it's affecting the tension and quality of my knitting, too.
I've tried holding the left needle up, but my stiches slip off sometimes, and even when they don't, I have a difficult time moving completed stiches to the right needle. Do I just need practice holding the left needle up? Please advise! I'm terribly uncoordinated.
(And yes, I know I sound ridiculous :))