I know this was sort of a silly question, but I have a real answer. No, breast size doesn't make a difference in breast feeding. In my human sexuality class we learned about the lactation process, but I forgot most of the science behind it... but I do remember that breast size isn't a factor and women with any size breasts can breast feed effectively. AND men (if given the right hormones) can breast feed as well. Also, their is a species of bat where the male breast feeds the babies.