Not to worry. Heres how to fix.
1st- unless its a genetic muscular deformity, you have a strength imballance.
2nd- you are not alone, my whole left side is stronger and bigger than my right. and I'm right handed.
3rd- the reason you have this imballance is probably because your also right handed and using the left side as stabililizing. which in turn is gonna make it stronger and grow bigger.
the cure: focus on the opposite now, try to use your weak side as the stabilizer, you want to use both sides as stabilizers but not in an imballace
you want to correct the imballance by doing this.
1- etra single arm flyes to build the muscle bigger on that side.
2- 1 arm push ups on the weak arm
3- 1-arm static hold in push up position
4- 1 arm dumbbell presses
5- weak-side presses, put a light weight on a bench press, and press it with only one hand, your right side. then use your left hand to just ballance the weight, dont press at all with the left hand. i actually just use my thumb and my index finger pinched together just to ballance the weight in
everbody has imballances. you just have to make an effort to correct them with a little extra attention. If the imballance is really bad. try training that muscle 10 sets of 10 everday until it is fixed. or use waterburys 100 rep program, maybe do 4 sets of 25 everyday.