I'm 14 and my right pectoral is WAY bigger than my left. Its a big difference when I looked it up in a mirror. I'm right handed but I thought it occurs more to people who are left handed and the weird thing is my elder brothers doesn't have that problem even my younger brother who is two years younger(left handed)than me doesn't seem to have the same problem as me! Can anyone tell me of a solution? It seems noticeble when I'm swimming. Does jerking with my right hand effect this? I need help fast!!

Note: My height is 178 cm and I weight 71 kg. I don't think my puberty is late or anything. I developed my right pec when I was 12 and its already two years and my left pec is still undeveloped.