How to help tenting in between my breasts after a BA? (Photo)

At two years post-op, your tissues have healed and matured and nothing other than revision surgery can improve this. Note that all 5 answers thus far (prior to my answer) involve more surgery--there is nothing (other than more surgery) that you can do (including thong bra) that will re-attach the stretched tissues between your breasts.
The problem is skin that is youthful and taut, coupled with implants that may be exactly the size you wanted, but are too big (tight) for your chest/breast skin. That's why some answers talk about smaller implants--think two basketballs beneath a blanket vs. two baseballs beneath the same blanket. Too large and/or too close equals more "tenting."
With breast implants in this situation, it's called symmastia (or synmastia), breadloafing, or most commonly, uniboob. 
The vast majority of plastic surgeons place augmentation implants beneath the muscles because of clear advantages in minimizing risk of capsular contracture.  .  . despite the occasional disadvantages of activation distortion and slightly more discomfort and surgical difficulty. Some surgeons still go above the muscles because it's easier, quicker, less uncomfortable for the patient, and sometimes "better in cases where there is breast ptosis" (droop or sag), than going below the muscles. (You had no breast ptosis, so you and your surgeon will have to answer the "Why" of above the muscles.)
HINT: "My surgeon has been no help" may help you understand.
Going below the muscles and maintaining the muscular attachments to the sternum will avoid most symmastia, but too large and/or too close can still cause this! So revision below the muscles is another approach to dealing with this issue, but what to do with those two above the muscle cavities that are now empty? Hope both of the old pockets "snap shut" and stick down (heal) perfectly without collecting blood or serum? How about two drains? (Not with implants, I hope)! Tape both side of the skin up till it heals in place (weeks)? Or just stay in the same pockets and try to suture the medial capsules down to the sternum (bilateral caspsulorrhaphies) with new smaller implants, or tighten the pockets and use the same implants in now-tighter, smaller spaces, making the beasts more firm? Lots of tough choices!
BTW, although this is straightforward surgery revision for experienced breast surgeons, it is NOT a quick, easy, or inexpensive "touch-up" surgery. (HINT: "My surgeon has been no help" may have something to do with this as well.)
So, to answer your last question, you can return to your original surgeon, who MAY charge an existing patient less, though usually only for the first year (review your consent and the written information provided by your surgeon regarding secondary or revision surgery). 
Or, you can go to another experienced, ABPS-certified, ASAPS member plastic surgeon who does lots of secondary breast surgery and pay for the surgery required. With new implants, this can be as much or more than the original BA surgery, especially if you initially went to a "cosmetic surgeon" who is not a "real plastic surgeon," or someone who may have the proper credentials but has less skill, experience, or ethics. Unfortunately, both types of these doctors exist, and they will happily take your money, do subpar surgery, and then refuse to deal with the suboptimal outcome. Your choice. Sorry.
Be safe, consider your options, get virtual consults (for the time being), and when elective surgery resumes, proceed with a well-reasoned revision. Best wishes! Dr. Tholen

Good afternoon!Your PS overdissected your middle, and therefore the tenting/synmastia has happened. The correct repair is the Original Internal Bra, my strong permanent internal suturing technique which reattaches the soft tissues to the breastbone, correcting the tenting and providing you with real cleavage.

The tented appearance between your breasts is called Symmastia. You have a pretty mild form of it, but it's understandable why it bothers you. It is a known potential complication of having breast implant surgery. Fortunately revisions are possible. For more severe cases ("uniboob"), revision surgery is complex and not all plastic surgeons do it. For milder cases like yours, revision surgery is easier, but still may have its challenges. You would not need a new breast augmentation, but you would need revision surgery which is a different operation. Depending on the techniques required this can cost less than, the same as, or significantly more than what you paid for your breast augmentation. In some cases the same implants can be used, saving some money there, but in your case I would recommend going with different implants for multiple reasons.