I'm 4'11, 92lbs, 12 BWD. Is 210 Cc Moderate Enough to Achieve a Full B Cup from an AA Cup?

Unfortunately, you have not told us your bra size just your cup size.  If you are a 32 or 34 each 100 cc's of implant corresponds to 1 cup size change.  If you are a 36 or 38 each 200 cc's of implant corresponds to 1 cup size change.  From this, you can calculate the size implant you will need to achieve your desired result.  Silicone gel implants placed retro-pectoral look and feel more natural and are less likely to ripple.

Best Wishes,

Gary Horndeski, M.D.

Thank you for your question. While this is a question best answered by your surgeon after having examined you, in general the difference between the two sizes that you mentioned are very small. I would recommend having a discussion with your board certified plastic surgeon again and undergoing Vectra 3-D imaging for you to visualize postoperative changes between those two implants. I find this extremely helpful for patients to visualize the size and shape of their breasts with proposals of different size and shape implants. 

Depending on your goals and objectives, either 210 cc or 240 cc are reasonable options. The size of the implants are based on a combination of a patient's goals
and objectives and her anatomy. In order to provide a natural looking
augmentation, the surgeon needs to evaluate many factors including soft
tissue coverage, skin laxity, chest wall width, breast imprint width,
the shape of the breasts and relative level of constriction to ensure
that the breast implants are appropriate for your body. Consult in
person with 3 experienced and expert board certified plastic surgeons to
understand your options.

In order to make an accurate size recommendation, I would need to assess your chest wall and breast mound measurements and characteristics.  Unfortunately, there is not a general rule of thumb or objective criteria to implant selection.
Your plastic surgeon will perform several measurements of your chest wall and breast anatomy and determine a range of implants that both fit your chest wall and reach your desired goals.
The next step is to try on this range of implants in the office with your doctor.   The key to this success is showing your surgeon the body proportion you desire with a bra sizer and allowing your surgeon to guide you to the right implant.   It will be much easier to communicate in implant cc's than cup size when determining the appropriate implant for you.
I wish you a safe recovery and fantastic result.
Dr. Gill

the difference between the two sizes you are contemplating is significant only because of the smaller original size of your breasts and chest. proper sizing can only be performed with an examination and measurements

Clearly you are a petite woman and so I agree with the choice of a smaller implant. That said, when choosing between two similar sizes (an ounce between the two) I would recommend choosing the larger one. 

Options for deciding on  a breast  implant size is dependent on many factors.  Some of the factors are presurgical breast size, tissue laxity, breast and chest measurements , type of implant and patient desires.  It is best to be evaluated and discuss these issues with your plastic surgeon.

There are many ways to help a patient determine an optimal implant size to meet expectations.  There is not much difference between a 210 and a 240 cc implant.  With a breast base width of 12 cm you may want to consider the larger implant.  

The plastic surgeon you are using should have samples you can put in a bra to give you an idea as to what size you will be. 

Small women can have nice breasts and still look normal to other people. What's most important is what size will you like? Choose a bra you want to wear after surgery and put different sizes in the bra in front of your breast until it fills out the bra the way you want. This will show you the exact amount that's going to be added to your breast and show you how both will fill out the bra. Try on some clothes over this and choose different sizes until you're sure you have a size that you think will be too big for you. I suggest try sizes up to 300cc. Then try smaller sizes until you find the largest size you feel you can tolerate. My experience suggests that's the size you'll most likely be happy with a few weeks or months after your surgery. When you first unwrap don't be upset if you think you chose too large wait awhile before deciding for sure. After you become accustomed to your size they soon feel more normal and most women are happier when they choose the largest of the sizes they are contemplating. I think this is due somewhat to reduced swelling but more often just getting used to the more normal size. Good luck.