Would the 600cc Mean Double DD's? 37yr 126 Lbs 5'4 Looking for Full/big D.

There have been many attempts to estimate how much larger (by bra cup size) a woman will be for a given implant size. Ultimately, bra sizes vary greatly from manufacturer to manufacturer and is an imprecise measurement of breast volume. A ptotic (sagging) breast requires a larger cup size than a full lifted breast because the bra cup is supporting the breast to a larger degree in the ptotic breast.

Many surgeons use implant sizers to help patients choose implants with great success. A newer technology that we have found useful is 3D imaging. Both techniques will give you a very good estimation of how much larger you will be after surgery. Either way, focus on the look and appearance of your breasts rather than the cup size.

For your stated goal, 600 cc is a reasonable recommendation. However, it may not look natural. 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.

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