As a reviewer for Blue Cross/Blue Shield for many years, I can tell you that your surgeon will need to document back pain, neck pain, shoulder grooves from bra straps, rashes (intertrigo) beneath your breasts, and perhaps even numbness in your 4th and 5th fingers from bra strap pressure on the nerves to these fingers (in your lower neck/shoulder area). This list is subjective and virtually every breast reduction patient with large breasts has all if not most of these symptoms to some degree. That's the "easy" part.
Then comes the mathematical computation (the Schnur formula) that uses your height and weight to determine the exact minimum amount of breast tissue that MUST be removed in order to qualify for insurance reimbursement. For you, this weight is 606 grams per breast based on your stated height of 5'8" and weight of 180lbs. Since 1 pound is 454 grams, your surgeon MUST remove AT LEAST 1 1/3 pounds per breast or YOU will get the entire hospital, anesthesia, and surgeon's bill. This varies but can be 10-15 thousand dollars or more!
Many women who wear large bra sizes actually have more droopy breasts than large breasts, so it is critical to compare an actual breast implant weighing 600 grams (for your example) with one of your breasts, because once the 606 grams is removed, your breast size and shape is determined by what is left behind. I find that many women, after doing this simple test comparison, realize that they will require nearly complete mastectomies in order for insurance to "cover" their surgery. This is NOT a good solution, since the only recourse now that your breasts are too small for the rest of your body are breast implants (which you have to pay for yourself). So if you don't qualify, have only the amount of tissue removed that leaves you with pleasing and proportionate breasts, which may actually end up being a "cosmetic" breast reduction or full breast lift. Sure, you will have to pay for this, but it's significantly better than having to undergo two operations when the "correct" one is actually better!
Of course, if your breasts are truly as large as your bra size seems to indicate, your surgeon may be able to remove 606 grams or more from each side and still leave you with attractive proportionate breasts! Best wishes!