Thank you for your question! Your queries can best be addressed with an in-person consultation and a breast exam. The implant size has to be chosen in relation of your preferences, your breast anatomy, characteristics and boundaries. Only when the implant is tailored to your breasts, then you can get natural-looking results. The more you deviate from the proper fit, the more fake your breasts will look. An evidence-based method to identify the implant size is called tissue-based planning. The planning takes into account the effects of implants on tissues over time, risks of excessive stretch, excessive thinning, visible or palpable implant edges, visible traction rippling, ptosis (Sagging), and breast tissue wasting. The planning involves making certain breast measurements such as the base width of the existing breast tissue, breast skin stretch, and nipple to inframammary fold distance. The implant size that will be identified will be the one which will adequately and appropriately fill your breasts while keeping long-term results under consideration. Finally, with regards to the pocket of implant placement, I would like you to know that the decision to go behind the muscle or over the muscle has to do with the amount of soft tissue coverage – “padding” you have under the skin. Choosing a pocket that is tight with sufficient soft tissue coverage not only prevents implant visibility, palpability, and risks of excessive stretching on the breast, but also excessive implant movement into the outer or inner sides of the breasts. A hand-in-glove fit for the implant allows for a natural and long-lasting result. Your surgeon will do a pinch test in the upper pole of the breast to see how much “padding” you have. If you have less than 2 cm, then you do not have much padding and it would be best to go under the muscle. Generally speaking, if your ribs are visible under the muscle, then you do not have much “padding.” If however, you have more than 2 cm of tissue, then you have the option to go over the muscle or under the muscle Which pocket do you prefer? OVER THE MUSCLE If you are hoping to fully preserve the functionality of the pectoralis major muscle due to athletics or body building, or if you have a shapeless, constricted, tuberous, sagging breasts without cleavage, then over the muscle may be a better option. · Over the muscle implant placement causes less trauma to the chest muscles, and the implants will not be subjected to any pressure or injury due to muscle movement. · The implant can directly apply pressure on breast tissue to shape the breasts. · However, over the muscle implant placement may have higher risks of breast tissue wasting, interference with mammography, and capsular contracture compared to under the muscle placement. · Higher risk of implant visibility and palpability is possible if you are thin, and this can be fixed used fat grafting where areas with less tissue coverage are filled with your own fat to provide better contour and coverage. UNDER THE MUSCLE Under the muscle (partially submuscular) is a preferred option for many surgeons because the muscle helps to maintain a slope for the upper pole while allowing for a curvature in the lower pole, while over the muscle will mostly make your breasts appear round and augmented. · In thin patients, additional coverage by the muscle reduces the risk of implant visibility in the upper and inner sides of the breasts. It also reduces risk of synmastia, and provides less interference with mammography and breast imaging. It also brings lower rates of capsular contracture. · However, under the muscle implant placement may allow the chest muscles to put pressure on the implant distorting the breast shape and position in the long-term. You may experience more pain following surgery due to the dissection of some muscle attachments and you may lose strength while flexing your chest muscle and is not suitable for athletes and body builders. All this being said, if you trust your surgeon and their judgment and the decision-making method used to choose the implant size, then you should be in good hands. Make sure to fully and comprehensively share your desires, expectations, and concerns to avoid miscommunication and post-operative concerns/regrets. Hope this helps, and best of luck!