The right side of your brain controls the left side of your body,
so it's not unusual for your right side to be the strong one and
your left to be the weaker side.

As far as being bigger, most of us are born that way, but Did
you ever see a pro tennis players tennis arm? The side most
used is going to be the strongest and most developed.

Ambidextrous I am not. My left side has always been my weak
side, so I was glad when MS chose to strike that side harder and
leave my right side stronger.

Most people do have one side that is bigger than the other. Sometimes it's not noticeable and other times it is. My left calf has always been bigger than my right. However, it's my left leg that is weaker than my right. My right hand is slightly larger than my left and it's my right hand that, by testing, is severely impaired. My left foot is bigger than my right foot and when buying shoes I try on the left side first.

Strength wise and in terms of MS, my left side is where I have most of my trouble from the eyes all the way down to my feet. My right side acts up every now and then with nerve pain and spasticity but not as much as my left side.

When talking ambidextrous, I am right-hand dominant but can use my left hand effectively, not as good as my right but I can use it.