How do I get my doctor to go bigger on the breast implant?

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.Keep in mind that every patient undergoing breast augmentation surgery should understand that their anatomic starting point will limit the outcome of breast augmentation surgery.    In other words, a patient's starting anatomy will limit how large of a breast implant can be utilized safely. The use of a larger breast implant (than what is safely "allowed" by the patient's anatomy) can be problematic;  potential problems include breast implant displacement/malposition issues ( such as bottoming out, lateral displacement, symmastia...)  and/or significant breast implant rippling/palpability.
 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.
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 "bigger" 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. 

Thank you for your question! I recommend a follow up conversation with your surgeon to discuss your concerns. It is possible that your anatomy will not support an implant of this size or your doctor may have other concerns that they have not communicated to you. You may also wish to seek a second opinion from another surgeon. Try to find one with 3D imaging technology such as VECTRA that can help you to visualize how various size implants will look on your frame. Best of luck with your surgery! 

Randyisdandy this operation is all about you. If your doctor won't give you what you want, find another doctor.Before you jump ship, listen to your doctor's concerns.  Be sure you understand what the doctor is saying and if you still insist on the size you want vs. the size he recommends ask him if he is willing to give you what you want.  If you are all in with this doctor, either go with what he wants, tell him you are willing to sign a waiver to get what you want, of find a surgeon who is comfortable with larger implants.A second opinion is usually not a bad idea anyway.Best of luck to you.sek