having a 34" bust goes well with a C cup for me. I think its just important to imagine yourself a a female and what size would go well with your frame. I'm a painter and so I spend hours moving body parts millimeters on canvas. if the breasts are too big (in a painting or in life) it will make you or the painting look awkward. too small is always better than too big. some GG naturally have big breasts on a small frame, but this also draws a lot of attention to them. If your trying to blend in you probably don't want to attention that big breasts can draw.