It depends how much body fat you have and it isn't always a hard and fast rule. My mum and sister are about the same, size 16 to 18 with C to D cup, whereas I'm size 8 with A to B cup and a different body type. I started hormones at 19 and have been on them for six years, over which time I have fluctuated between A and B. Most people I know have more growth than me though, I don't have much because I don't put on any weight, I've been the same give or take five kilos for the last ten years.