One boob bigger than other...

I've heard this is so normal & that "only you notice it", but I feel as if mine is a big difference. I'm already a DD with a tiny ass figure so it doesn't even out. My left boob almost looks like it's a whole cup size bigger. Is that even normal? Ive checked myself for lumps & bumps but other than all the normal lumps there's nothing. It's so frustrating because summer is coming up & I don't want to feel even more insecure than I already do.