150cc-190cc for subtle change with pectus carinatum? (Photo)

You pose a good question.  I would urge you though to concentrate on the final appearance and not concern yourself too much with the exact number in cc's of the implant.  The most important thing you can do is see a board-certified plastic surgeon experienced in breast augmentation.  Appropriate measurements will be obtained and often the exact implant size can only be determined intra-operatively.  A number of factors determine the exact shape you want with implant size being just one of them.

My initial thought, based on the description of goals, is to choose the smaller of the implant choices.  One question that might be helpful to patients in your situation: would you be more disappointed if you are slightly too large or slightly too small? 
My best advice: more communication.
It is definitely worth spending more time (prior to the date of surgery) with your plastic surgeon to discuss further.  As you know, 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.
Ultimately, 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.
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 "A or B 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. 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. 

Dear Vanessa343Thank you for your question and photos!  The implant size is a difficult choice.  I would advise that you stay with the smaller size - and a lower profile , as your right breast is fairly lateral on your chest wall and the chest is angled lateral - relative to the left breast.With Warm RegardsTrevor M Born MD