Actually breast / cup size works in such a way that the same size cup will look about the same scale regardless of what band size it is attached to. That is to say that a 32C cup is smaller than a 36C cup, which is smaller than a 44C cup.
Find a cup size you like, B/C is probably good for most of us if we desire to pass - though D's are certainly passible on bigger frames (otherwise, hell get the EEE cup and be the girl you always dreamed about) then find the band size that is comfy, plug in your preferred cup size, and go to town. Literally.