What implant size is perfect to me? 5’7”, 125 lbs (Photo)

Thank you for the question.  Online consultants will not be able to provide you with specific enough advice to be truly helpful.  Ultimately, careful selection of plastic surgeon and careful communication of your goals (in my practice I prefer the use of goal pictures, direct examination/communication in front of a full-length mirror, in bra sizers, and computer imaging)  as well as careful measurements (dimensional planning) will be critical.
 
***Given your concerns, it is definitely worth spending more time (preferably prior to the date of surgery) with your plastic surgeon to discuss further.  One question that might be helpful to you: will you be more disappointed if you are slightly too small or slightly too big?  It will be important for many reasons, that you feel comfortable that you and your plastic surgeon are on the "same page" prior to proceeding.
 Generally speaking, the best online advice I can give to ladies who are considering breast augmentation surgery ( regarding breast implant size/profile selection) is:
1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals. 
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. For example, I have found that the use of words such as “natural” or "C or D cup" or "perfect" etc means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on him who makes the bra; therefore, discussing desired cup size may also be inaccurate. Again, the use of computer imaging has been very helpful during the communication process, in our practice.
3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery, after the use of temporary intraoperative sizers.
I hope this helps. Best wishes for an outcome that you will be very pleased with.

I recommend an in person consultation with a plastic surgeon to discuss your goals and be measured. With my patients , I then look at pictures of women with similar measurements with different size breast implants. Placing the implants behind the chest muscle will help to make it look natural. My patients tell me that this process is very helpful in determining what size implant is best for them.Dr. Ted Eisenberg, Board Certified Plastic Surgeon and Author

Thanks for your question.  Since there is no way to say definitively over the internet which size would be optimal for you, take comfort in the fact that the surgeon uses your unique measurements and is able to provide you with a general range.  In many cases the board certified plastic surgeon can best be your guide as they’ve met with you in person and heard your aesthetic goals. You may consider doing 3-D imaging; however with nearly all the breast cases we’ve performed, we’ve found patients enjoy doing a live “try on” session where they actually can “try on” the implant in a non-padded bra in our office.  This does not give an exact measurement of outcome, rather it gives a nice idea of what to expect. For patients who desire a more natural look we like to recommend the shaped implant.  For patients who desire a more full, voluptuous look we recommend a higher profile implant (like Inspira). Remember that all breasts have at least some amount of asymmetry (we like to say they’re like sisters and not twins).  An in-person consult is the best way to discuss your questions.   Be sure to find a surgeon with the following credentials:  *Board Certified by the American Board of Plastic Surgery -- The gold star symbol   *A member of the ASPS (American Society of Plastic Surgeons) -- The circle symbol  *A member of the ASAPS (American Society of Aesthetic Plastic Surgeons) -- the Queen Nefertitti symbol with a Triangle.   My best, Brian Coan, MD, FACS