I would like to reduce the size of my breasts from a DD to a C cup, would I qualify for breast reduction?

Hello and thank you for your question.
I suggest calling your insurance company to see if this is a covered benefit for you and what the guidelines are. Schedule a consultation with a board certified plastic surgeon to discuss your options. Best wishes!

BRs which are medically necessary (i.e. you suffer back, shoulder, and neck "pain" with DOCUMENTED medical attention over a period of a YEAR) are typically covered by medical insurance.  If not, your medical insurance may try to deny you based upon a lot of things such as weight, lack of symptoms, lack of previous medical management, and lack of enough tissue that should be removed. 
Read your Medicare Secondary Payer medical insurance certificate of coverage. Determine what medical information is required for MSP to issue a pre-authorization or predetermination of benefits for BR surgery.  Then seek consultation with a board certified plastic surgeon who can evaluate your medical condition, discuss the pros and cons of this surgery as it applies to you, determine the amount of tissue to be removed, and help you in completing the paperwork required by your medical insurance company.  (Take all documentation you have accumulated to your board certified PS's consultation appointment.

Thank you for the question. Based on your description you may be an excellent candidate for breast reduction surgery.   However, much more information is needed to determine whether you should proceed with surgery, and if so when (timing).  In my practice, I individualize the “timing” of surgery based on a lot of information that is transmitted during the consultation process.
“Typical” patients who present for breast reduction surgery are women who have disproportionately large breasts, causing problems such as neck/back/shoulder discomfort, postural changes, bra strap grooving, skin irritation/rashes under the breasts, and/or difficulty with activities of daily living and/or exercise etc. There may be both physical as well as psychosocial “stress” caused by the disproportionately large breasts.
Reducing breast tissue mass and elevating the breasts on the chest wall tend to improve or alleviate many of the symptoms associated with the disproportionately large breasts.
Patients considering breast reduction surgery should also consider the potential downsides (risks/complications) associated with the procedure as well. Poor scarring, for example may be associated with the procedure.  Additional surgery may be necessary in the short or longer term for a multitude of reasons.
When the time is right, I would suggest starting with the American Society of Plastic Surgery and/or the Aesthetic Society of Plastic Surgery to obtain a list of well experienced board-certified plastic surgeons.
Then, I would suggest you visit a few surgeons whose practices concentrate on aesthetic surgery. Ask to see lots of examples of their work and preferably speak/see patients who have had similar procedures done.
Then, it will be important that you communicate your goals clearly with your plastic surgeon and make sure that you have realistic expectations prior to proceeding with any type of surgery. In regards to breast size desired, also communicate carefully. In my practice the use of goal pictures are helpful in this regard; a discussion of cup size can be confusing and imprecise.   Therefore, I would not suggest that you communicate your goals and/or base your satisfaction with the outcome of surgery on achieving a specific cup size.  I also find that the use of pictures is more helpful than the words “natural” or "proportionate” etc., which can mean different things to different people.
Many of my patients choose to have enough breast tissue removed to help alleviate symptoms while retaining enough breast tissue to remain proportionate to the remainder of their torso.Best to check directly with your insurance company to see whether breast reduction surgery is a “covered” benefit with your specific policy. Then, given that every insurance company has different “criteria”, best to identify exactly what your specific insurance company considers criteria for approval. Generally, the more documentation you have (for example, from your primary care doctor, physical therapist, chiropractor etc.) the better when it comes to obtaining insurance “authorization” for the procedure. 
This documentation and letter/pictures from your plastic surgeon will help you obtain authorization. Keep in mind, as you work towards your goals breast reduction surgery is one of the most patient pleasing operations we perform. Also, prepare to be persistent when dealing with health insurance companies. 

I hope this helps.