Let’s talk about getting older and boobs

So I’m not quite 30 years old yet. That’s not very old. And yet I have noticed my body changing in ways that I was not expecting for a few more years…

breasts

Why didn’t any one tell me about this? Is this happening to anyone else?

Size has not changed. Shape has not changed. There’s just a mysterious, over-night 3″ drop. Can I prevent this from continuing? Is this going to happen to some other part of me next?