Post pregnancy with 2nd, I was 36 D, I am not busting out of my 36DD and Have to go on a hunt for a bigger size. It sucks for me because all DD's and up in store are 38 aand 40's and I am not that big around so the cups fit but the band is loose.
I'm still a flimsy 34B PP and while pregnant I'm 36B. I breastfed with my small boobies too. Maybe I'll get lucky and make it to a C cup after this pregnancy. ;)