Which profile will give me a natural look? 4.3 cm (370 ml) or 5.3 cm (460 ml)? (Photo)

Thank you for the question and picture. Unfortunately, online consultants will not be able to provide you with specific enough advice to be truly helpful. Given your questions and concerns, you'll be best off spending additional time with your plastic surgeon communicating your goals carefully. Keep in mind, that there is no reliable correlation between the breast implant size/profile use and specific cup size achieved.
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're 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. I have found that the use of words such as  “natural”  or  "C cup”  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.
 The use of computer imaging technology may also be very helpful during this communication process.

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.
I hope this (and the attached link) help.

Thank you for your question.There is more than one right answer.  For clients who have a narrow but tall chest, such as you, I like to use the Sientra Textured Shaped Classic Base Moderate Projection.  This is a "Gummy Bear" form stable implant.If your base diameter is 13 cm, then a 350 or 400 mL implant would fit your dimensions nicely and give a natural look.I have attached a web reference as an example of before and after with this type of implant in patient with a high chest.I hope this helps.