I think you’de be a large C cup 
My mum had 300cc unders from “nothing” (not even training bra size) and this took her to a perfect C. She’s a petite frame also and no breast tissue or even much body fat really, so her breasts are all implant and this is what size it took her too. I think they look great and noone can tell in her clothes or one piece that they aren’t real, it’s only without a bra they are obviously abit too perky to be real, as she’s 50 now, lol.