Clear communication with your plastic surgeon is important in achieving the desired goals of the patient. I like to communicate with patients with “goal” pictures. During surgery, I use temporary sizers to determine the size/profile that will give the patient the look she is looking for. Trying to predict the size of the implant preoperatively is not ideal. I think it is too much responsibility for the patient to choose the size of the implant. Ideally, the surgeon would make that determination once he/she is in the operating room with sizers in and examining the patient in the upright and supine position. There are many variables that come into play when choosing the correct implant size (how much breast tissue the patient currently has, the shape of the chest wall (concave vs. convex), etc..
On this site, I do my best to give advice without a physical examination but I want you to know that a physical examination by a board certified physician is always the best way to get the most accurate information.