I am a 36gg in bra size I have really big breast and am looking to reduce them due to a lot of back pain (Photo)

Thank you for the question and picture.  Based on your description, you may be an excellent candidate for breast reduction surgery.  Generally speaking, the “ideal” patient for breast reduction surgery is one who presents with relatively large breasts in proportion to the remainder of her torso.  These patients often present with neck, back, shoulder discomfort, bra strap grooving, postural changes, and occasionally with rashes/infections. This operation tends to be one of the most patient pleasing operations we perform.
  Your next step may be in-person consultation with well experienced board certified plastic surgeons.  Ask to see lots of examples of their work and make sure you feel comfortable with the quality and consistency of the work performed. During these consultations, you may be able to see other patients ( similar to yourself) who have undergone breast reduction surgery.
Ultimately,  you will need to decide whether the “pros” ( benefits) of breast reduction surgery outweigh the potential “cons” ( potential risk/complications).  You may find the attached link helpful to you as you educate yourself about the pros/cons of the breast reduction procedure.
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. I hope this, and the attached link, helps.

If you're having back pain and neck pain secondary to your heavy breasts. You need to document this through your primary care physician with either treatments by him or her or referrals to specialist to treat your back pain.if all of these measures fail it would be advisable for you to seek consultation from several board-certified plastic surgeons concerning breast reduction

You might very well be a good candidate for a breast reduction but you would need to be seen in person. Best of luck.