Cup size is determined by measuring around your rib cage underneath the breast and comparing that measurement to the widest part of your breast. Therefore, it is all relative. My guess is that you will be well over a double D breast if the bra is fitting properly. Please don't obsess about bra size. It is an arbitrary number. Focus on how you look and feel in your clothing. If you are happy with how you look and feel, forget about the number (and letter) on your bra label.
Congratulations on having undergone the revisionary breast surgery. At some level, I am sure that you are aware that it is too early to evaluate the outcome of the procedure performed. For future patients considering breast augmentation or revisionary breast surgery, I would suggest that they do not base their communication or level of satisfaction with the outcome of surgery on achieving a specific cup size. Cup sizes will vary from one bra manufacturer to another and cannot be used as a reliable communication tool. More helpful preoperatively will be communication with the help of goal pictures, computer imaging... Best wishes; hopefully, you will be very pleased with the longer-term outcome of the procedure performed, regardless of the specific bra size achieved. Instead, I encourage patients to evaluate the outcome of the procedure performed based on the overall “look” and improvement in proportionality of upper and lower body.
There is no way to determine cup size, and cup size varies with every bra manufacturer. Dont obsess about cup size and communicate with your surgeon about your goals. Clearly 400 cc on a 5'0 woman will look very different on a woman 6'0. Worry about your surgeon understanding your goals/outcome and not the ultimate cup size. That is a non-scientific measurement for a scientific procedure.
Best of luck,
Vincent Marin, MD
San Diego Plastic Surgeon