Well band 32 bras fitted 'some' back in 2006, but I changed to band size 34 in 2007 because 32 size would leave deep red marks in my back where the strap was. I fit 34 A bras mostly, I haven't tried all brands, its a bit depressing to be bra-shopping when you're this small (and this poor).
As for my malformation, I found out online that it's called pectus excavatum. Or concave sternum (the joint between the ribs in the middle of the breasts).
Mine is not that deep, maybe 1 inch deep, 2 inch diameter. Potentially it would increase my cleavage...given I had enough breasts to have visible cleavage anyway. It's supposed to 'get worse' with age (puberty), but mine actually got less worse, or not worse anyway. I've always kept a small bone shape.
It's a rather common malformation, happening in 1/300 births and 3x as much in male children than female ones (according to that one site I saw about it).
My grandmother, and a (female) child I once met some years ago, both have it as well. It's said to be possibly stand alone, or as a symptom in a few conditions (including Noonan syndrome). I'm not sure what it is in my case, it never was investigated.
It affects the ribs (who are more rounded since they curve even more inward), the ribcage's overall form, and can possibly affects lungs and the heart if it's too pronounced (nothing in my case). It's possible to cosmetically 'repair' it, but is mostly done when its life-threatening. Breasts and cleavage could conceal much of it.
