Well it's hard to say not having been there, but I think that if I ever gained and then lost a large amount of weight, I'd consider surgery to remove loose skin part of the "fixing" process towards maintaining a healthy, functional body, and not vanity at all.

Deedolce - the flattest-chested girl I ever knew (I swear, her chest was like a boys with 2 pea-sized bumps on it, she looked about 11) is also outgoing, funny, outdoorsy and is now married and has three children. You'd be surprised how many guys really don't care much about boobs.

And I hate the assumption that I'd rather be "bigger" than A/AA too. I wear unpadded bras, and dammit, that's what I look like!