My right hand is bigger than my left. My right foot is bigger than my left (just a bit, but enough) Its a common thing for people to not be equal, but if this is a NEW thing, its time to tell your MD.

PT, and other exercises may be able to help.

It may just be that your muscles are built up on the other side to compensate for lack of use from the weak side. we tend to naturally compensate when a peice of our body slows. The blind have extraordinary hearing. Those who have had a stroke can learn to write with the other hand.