Maybe I'm old fashioned, bit big, small or medium, breasts would not determine who I was attracted to. They are just part of the package. Besides, even if the woman has beautifully shaped breasts, eventually, like everything else, they will succumb to age. Initial attraction for me is smell ( as in clean, light perfume), eyes and personality. I do like shapely legs however.
Size of breasts and size of male packages really are the same when you think about it. Both are things that men and women are conscious about, both cause anxiety if the man or woman feel their own parts are somehow not adequate, and neither one are a good indicator of what sort of partner the owner of said parts will be.
If all you want is sex and nothing else, I suppose it would matter. If you are looking for something beyond that, its a poor place to start. In any case, if a woman feels that she has to add to her size for a guy, perhaps he isn't worth pursuing.
Sam2