I've been on HRT for 19 months:
Overbust: 32
Bust:36
Underbust: 31
Waist: 25
Hips: 34.5
I'm 5'5 and suffer from other conditions, so these numbers houldn't be taken as a representation and also it doesn't look as good as it sounds---at all. I look like a C cup, at best, but yeah my waist looks very small combined with very narrow shoulders. But still only a cutish butt, nothing big.