I have actually large breasts (not just pure fat bags), and they "developed" pretty much overnight. This left stretch marks radiating out from each areola, all the way around. It happened when I was 12. I suffered in silence, feeling like I'd never be able to show them to anyone. Luckily they became not very noticable within a couple of years, but they're still there, I'm at peace with them, and I did not have to post pictures of them all over social media to accomplish that.