I may be wrong but 1st baby, didn't breastfeed long at all due to PND (2 weeks max) and boobs stayed the same, pretty unaffected by pregnancy as well.
2nd baby, pregnancy didn't seem to have too much of an effect on boobs. This time breastfed exclusively for 12 months and now I have stopped I've realised my breasts are at least 2 cup sizes smaller than before this baby. My old bras are massive on me, I used to have a lovely cleavage which non-existent now. They're just small and saggy as well now.
I really suspect breastfeeding for so long changed them? But everywhere says it's a massive myth and that it is pregnancy, not breastfeeding, that causes the changes.
Feeling a bit sorry for myself as I look rubbish in a lot of my old dresses and my boobs were one of the nice things about me that I actually liked.