Hello,
I have two shoulders that sublux so I can't go over head,but like you said you just do it where you are comfortable. I told my Tai Chi instructor and she said its for your health so go however far you are comfortable. I am also careful with my legs because I have loose legiments. Even though I have these limitations I can do the tai chi decent. I practice it now in my living room so if I don't do everything perfect it doesn't matter. I hope you found these comments helpful. Take Care hope you are having a pain free day.

Lmjunior