Okay, I have absolutely no clue how useful (or not!) that might be, but here are pictures as promised!
I cut off the heads so you won't know it's me.
First I tried with something fitted. Unfortunately it's black so you can't see anything, so I won't post the pictures. Except one of my torso from behind for the shape of the waist. You can see it barely gets smaller, and definitely not suddenly (getting suddenly thinner makes it looks like it's the ribcage as stated previously). Of course that changes from one woman to the next.
So then I switched to a different-coloured shirt, but it's also looser. As a result it doesn't follow my shapes very much.
So I "tucked" the shirt under my breasts so you'd see better. Not sure how conclusive that was
Now, in all of these pictures, the breasts look round(ed). Why? Breasts aren't round, right? They're kinda pointy where the nipple is.
Well that's because of the clothes. They're pressed against the fabric, and that makes them rounder. The only way to keep the exact shape while wearing clothes is to wear clothes that already have the shape of breasts. Like "pockets" or something. Otherwise it's either tight and shapes the breasts, or loose and then you can't see the shapes anymore.
Not sure how useful any of that was... Naked pictures would be more useful but something tells me posting them here would be frowned upon.