Abnormal breasts?

I’m 18weeks 5 days through my pregnancy and from very early on I’ve had one breast bigger than the other as they’ve got bigger. (Before I was pregnant this was the case too) but even though they’ve grown this has stayed the same and I seem to notice the size difference more. Also one areola is noticeably darker than the other. I had a nipple piercing when I was younger in the higher breast with the lighter colour, I don’t know if this affects it at all but I have two different shaped nipples due to this. I have told my midwife but she wasn’t too concerned and said if I am really worried to see my GP. Just wondering if any one else has had any of this happen during pregnancy too or whether I should be concerned. Everything feels normal but as this is my first pregnancy I don’t really know what is normal for me! Thanks xx