This may be something you have not taken a good look at, but what about your hips? Do you have exacerbated lordotic or kyphotic posture? The reason I ask is that if the hips are out of alignment, it is very hard for the middle and upper back to be in alignment either. If you do get the hips back in balance, then most likely your other issues will be far less severe and problematic.

Take a look at yourself in profile view in a mirror with your shirt off and see if your hips tilt too far forward or backward. That will certainly put your back out of whack. I strongly suggest dealing with that issue in conjunction with any trapezius and serratus work.

I found a book that I like for aligning the hips that can be done at home. It is written by an expert in the field and is pretty simple to follow. It is called the S.M.S. Back Program. I recommend checking it out...