hi there!! i was a 34b after having 2 kids!! i did used to be a very pert c cup, but they sagged and went minging! and i had 340cc overs put in and an upllift and now i have 32e boobs!! so you def guna get a good size with already being a c/d cup! i reckon if you had just a 340cc you would measure a ff!! easily!! what ever sizes you are offered go for the biggest you can get!! XXXXXX