Gaining weight for boobs?

So I'm 17 today, and I still wear a 30-32b. Id say I'm pretty skinny, but my legs and butt are bigger than others and I look quite disproportionate. To gain self confidence I'd like to gain weight to see if my boobs will get any bigger, but I'm having an issue determining whether I want to do it or not. I've always been pretty behind with developing, so I don't know if I should just wait it out. If I do gain weight, I'm scared that it'll all still go to my thighs, and if I do gain weight and try to lose it again I'll just end up losing my boobs lol. Any thoughts??