I'm curious about breast fat grafting!

I have lived my entire life with an A cup.

Then, as I gained weight rapidly, my breast size also increased, but I know well that it's not breasts, but fat ㅠㅠ

I'm worried that if I go on a diet and lose weight, my breasts will also shrink and sag unflatteringly.

Even now, the chest shape is bell-shaped, so the upper chest is sunken.

Can fat grafting give you firm and large breasts?

I'm worried about surgery not because of the size, but because of the shape.