Shoulder Issues: Thoracic Extension & Rotation

ive been having shoulder issues for a while now. mainly very poorly developed upper back basically due to being completely ignorant about proper training and how to body functions.

so lately ive been trying to balance everything out but i have a very very hard time getting anything in the back to really fire. besides upper traps and lats. basically want to strengthen middle and lower traps. my main issue is that my left side is more rotated than my right, what i mean is that my left upper trap middle traps are more developed than my right. my right chest feels tighter. i feel like i have more t spine rotation on my left side than my right which seems to be causing problems on both sides. i have a really hard time even retracting my shoulder blades. anyone else ever deal with this? and exercises to correct? thanks

Larry10 has some good stuff on back issues. Try the video he posted in a thread called shoulder bugging me

thanks man, ill check it out