Thank you for your question and photo. As you undoubtedly know, a precise treatment plan or specific implant recommendation can only be determined with a careful examination and detailed discussion with your plastic surgeon. The most important single number in all of your measurements is the Base Width Diameter of your breasts to determine the optimal width of your implant. A low profile implant is what you will indeed require based on your expressed wishes of a very conservative augmentation. Volume (300 versus 400), is far less significant than implant width and projection. Implant width is similar to shoe size. The implant literally needs to fit into your breast and chest. The volume and projection are what will determine the “look” you want, similar to the style or type of shoe you would select. The term “natural” can mean different things to different people and the profile of the implant does not necessarily determine that. You can certainly achieve a “natural” appearing result with a high profile implant if properly selected, but as a rule, the larger the implant and the higher the profile, and certainly if the implant is positioned too high, the greater the chances you will look “augmented” because of exaggerated upper pole fullness or convexity. In my practice, besides a thorough interview process and physical examination with careful measurements, we use on lay sizers within an unpadded bra to help you understand what you are likely to look like in a bra, bathing suit, or T-shirt with a given size implant. In addition, and this is critical, we ask all of our patients to provide us with photos of their desired final look, with images of women’s breasts that most closely resemble the look they are trying to achieve. This serves as a visual guide that thankfully rarely leads us astray. The most common reason for patient disappointment after breast augmentation is size-too big or not big enough. This algorithm which we have been employing for over thirty years has proven to be very successful. Because all of these factors can leave you quite confused, it is crucial that you select an experienced board certified plastic surgeon whose aesthetics align with your own, and with whom you feel comfortable. Don't be reluctant to seek a second or even third opinion if necessary to be sure and feel confident about moving forward with scheduling surgery. Expressing your desired cup size is notoriously inaccurate, and final breast size is the most common reason for patient disappointment after breast augmentation, either too big or not big enough. Take your time, continue to do your research, and allow your plastic surgeon to advise you specifically. Best of luck to you.