Will Mentor 400cc high profile over the muscle give me a fuller look? (Photo)

Good afternoon!
That sounds like an excellent choice based on your dimensions and photo- I think you're going to love them!

Thank you for the question and pictures.  Based on your photographs, I think that you are starting at a good place and should have a very nice outcome with breast augmentation surgery.   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.I think it is in the best interests of most patients seeking breast augmentation surgery to have implants placed in the “dual plane” or sub muscular position. This positioning allows for more complete coverage of the breast implants leading to generally more natural feel/look of the implants in the long-term. This position will also decrease the potential for rippling and/or palpability of the implants (which may increase with time, weight loss, and/or post-pregnancy changes).
The submuscular positioning also tends to interfere what you got the bonus with mammography less so than breast implants in the sub glandular position. The incidence of breast implant encapsulation (capsular contraction) is also decreased with implants placed in the sub muscular position.
On the other hand, sub glandular breast implant positioning does not have the potential downside of “animation deformity” ( movement/ distortion of the breast implants seen with flexion of the pectoralis major muscle) they can be seen with breast implants placed in the sub muscular position.
  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. Sometimes, it is necessary to seek several consultations before you feel comfortable about your choice.
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 “fuller look” or DD or E cup” or "silly" etc may mean 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, best not to discuss your goals and/or judge the outcome of the procedure performed based on achieving a specific cup size. The use of computer imaging may be very helpful during the communication process. The use of in bra sizers may also be helpful. In other words, use as many “visual aids” as possible during the communication process. I encourage patients to meet with me as my times as necessary, to feel comfortable that we are both on the “same page”.
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 generally select appropriate breast implant size/profile after the use of temporary intraoperative sizers and viewing the patient's chest in the upright and supine positions.
  
I hope this helps. Best wishes for an outcome that you will be very pleased with.

Has your surgeon thoroughly gone over the advantages/disadvantages of under the muscle vs over the muscle? If not, get at least one or two more opinions. Good luck!