I'm not sure how asymmetrical your proportions are, but SOME asymmetry is normal. I have been training for several years with minimal strength differences between my left and right sides, and my left side is still slightly bigger in most cases.
I have a theory about that. If it turns out that most people are slightly larger on their non-dominant side, and it is actually more muscle mass as opposed to fat deposits, then it may be an adaptation to make up for the lesser neural drive there. Most people have a larger left hemisphere, which controls the right side of the body. Hence why most people are right hand dominant. Just a random thought; it is not substantiated in the least bit.