One boob is bigger?

I just noticed last night that my left boob is bigger than my right. When you’re looking head on, it doesn’t look like much of a difference but when I’m touching them there is. I’m on bc pills and this is my 3rd period that I have purposely skipped. My boobs are a little more swollen and tender because I was supposed to get my period soon. From what I’ve felt, I don’t feel any bumps or lumps that I haven’t felt before. But it scares me because I just noticed...I guess I’ve noticed before too & there’s been times where I’ve noticed ones bigger than the other, but I usually forget it because I think they eventually almost even out. I’m only 22 but I know at any ago you need to watch out for signs or symptoms. Is this normal? Could this be due to skipping my period and being on bc pills???