(2) as we age and possibly nurse our babies, the breasts can lose their "buoyancy," if you will. That those who have unusually large ("mega") breasts (macromastia) can have these problems is an understatement. Many women with large breasts may also suffer from shortness of breath, irritation and even infection under their breasts, and other health problems. Even a perfectly fitted bra (and we know that most women don't wear well fitted bras) cannot entirely prevent this from happening. Many women experience permanent bra strap depressions on their shoulders from their having to bear the weight of large breasts.
(1) many, if not most, women who have just run of the mill large breasts (e.g., 38D) eventually experience chronic shoulder and/or back pain as a result. Just a side note to the LW: you didn't say how old you are but here are a couple of things to consider: