Am I sagging and am I a 34D? (Photo)

Hello, over time implants can descend lower than their original position, then the nipple looks relatively high on the breast mound.  This is called "bottoming out" - perhaps you are noticing this change over time.  Regarding your bra size, this is hard to determine from photos but you can have proper bra fitting to determine this.

Many thanks for posting your questionFist of all, it appears that your breast size is around a D cupHowever the issue that I see is one of bottoming out - it appears that your breast implants are sitting a bit low in the breast. Is this what you mean by sagging?If so, and it bothers you, then revision surgery might be required.The best thing would be to discuss with your plastic surgeonGood luck

I am sorry to hear about/see the problems you are having after breast augmentation surgery. I think your concerns are appropriate; your breast implants do seem to sit quite low on your chest wall, consistent with breast implant displacement ("bottoming out”).
It is probable that you are feeling the implants significantly along the lower poles of the breasts. Patients in your situation often complain of discomfort in the area of implant malposition. Also, consistent with the breast implant positioning problem, the nipple areola complexes seem to be sitting relatively high, because the breast implants have settled too low.  
I think you will benefit from revisionary breast surgery which will likely involve capsulorraphy ( internal suture repair). This procedure serves to reconstruct the lower poles of the breasts and prevent migration of the breast implants too far inferiorly. Associated issues with positioning of nipple/areola complexes should improve with this operation.
Make sure that the plastic surgeon who does this procedure for you can demonstrate significant experience with revisionary breast surgery.
I hope this, and the attached link, helps.