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

Size and Shape For Implants With A Long TorsoI can just provide general concepts. An anatomic shaped implant with a Tall profile is probably a good choice for you. A round implant will sit very low on your chest. Volume will change the cup size and the lower volume will be closer to a c cup for your.

Breast
augmentation alone will not solve your problems. Your breasts are too far apart, too low and
you require a simultaneous lift. I
recommend a new technique called Breast Augmentation with Mini Ultimate Breast
LiftTM. Using only a
circumareola incision it is possible to reshape your breast tissue creating
upper pole fullness, elevate them higher on the chest wall and more medial to
increase your cleavage. Through the same
incision, implants can be placed.
Aligning the areola, breast tissue and implant over the bony prominence
of the chest wall maximizes anterior projection with a minimal size
implant. Small round textured silicone
gel implants placed retro-pectoral look and feel more natural, are more stable,
less likely to ripple or have complications needing revision. Implant profile is irrelevant in the
retro-pectoral position since the muscle compresses it. 22% of women who undergo breast augmentation
alone require revision within 2 years because they are dissatisfied with the
result. Common causes of dissatisfaction
are over implantation or not performing a simultaneous lift when required. If you place 460 cc implants and do not
undergo a simultaneous lift, you will need a revision. Best Wishes,Gary Horndeski, M.D.

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.