You've already gotten good advice, but I just wanted to add that more than likely, that is the way your body is built - I know mine is. (LEft side produces quite a bit more.)
And, although pumping is different than feeding baby, I can still tell that my left side actually fills up more and baby gulps more from that side and drinks faster and it takes less time to get a let-down. I've had 3 babies now, and although they've prefered the left side, I always start with the right side. Always. It will never, ever catch up, but it's fine and it doesn't hurt the baby (although it's annoying to be lopsided, I know).
My first baby ended up just nursing on the left side for the last few months of nursing because it was too frustrating to try to get anything from the right side. I let him. It was fine and he nursed until he was 16 months old. I am trying to keep baby #3 on both sides as long as possible, but it one day he weans himself from the right side, that's ok too.