hi there, my friend was the same size as you, and a petite size 6, and i recommened her to my surgeon through Transform Cosmetic, and she had 340cc implants and now measure a perfect size large 32c to a 32d cup.
She has partial unders (under muscle) and they look lovely on her.
I do reckon with you being only smallish in chest department, you,ll be offered approx 280, 300 and 340cc.
im not sure if you have had your consultation yet, but if you do def opt for the biggest implant you can get, as there really isnt much difference between the 3 or 2 sizes they offer you.
my friends boobs look realy nice and not too big not too small.
I too had 340cc implants, but i had overs and was a 34b to start with so i achieved a bigger size of a 32e-32f, but the smaller you are to start with the smaller you,ll measure.
A 340cc would be perfect for you and your petite frame XXXX hope this helps, oh and one more thing, you must remember, implants sizes measure bigger but dont look as buig as the natural thing, for e.g i measure a 32f but only look a dd in clothes. XXX