I never did find out my mother's exact size but it was around DD-F range
I hit an A pretty quickly, buds (about golf ball sized) showed up after about a month and once they did the natural fat around them padded them out to fit an A alright allbeit a bit loosely
I'd say about two weeks ago (5 months into HRT) my 34A's started to get too tight on the boobs, so I bought a 34B which fitted much better, however i havn't been able to buy a replacement set so i've been making do with the old ones even if things are a bit cramped.
This morning I measured up and to my surprise my strict measures say C on the dot but i suspect this is because my my huge shoulderblades and general hourglass shape and pointy boobs adding an inch or so to the overbust measure, they don't look like C's more like large really pointy A's, if the nipples stay where they are and they round out properly I think I would be a large B/small C though.
Overall it's not something i'm obsessive about, I have boobs and that's the main thing, i'd rather stick to an A than have surgery on them to be honest, I really don't like the idea of implants