And what is wrong with my breast!?

I am 6 months post-op and Goal Weight! Go me. But my body is changing shape on weird ways every day. Now, my breast are smaller than they have been since puberty. I know that breasts are mostly fat, but one of my breasts has caved in on the top. It is seriously and literally concave. Is this normal because of my weight loss? Am I dying or do I just need to add "boob job" to my plastic surgery wish list?

Do you have any additional symptoms that would indicate a serious medical issue?

Normal. With massive weight loss we tend to lose upper pole fullness. A lift may not do much to address this which is why so many of us get implants. I chose to go with a lift only. I do not have any upper pole fullness, but with a good bra my breasts look great.