Have I got symmastia or tenting at 6 months post-op? (Photos)

Based on your description and photographs, I think that symmastia is not present but skin tenting is.   It is hard to know whether there will be improvement  of the skin tenting over time.  If, in the longer term, you have the right same concerns, medial capsulorraphy (along with the use of acellular dermal matrix in my practice) will likely be necessary to increase this space between your breasts implants and improve the skin tenting situation. Best wishes.

Dear BArecovery,
symmastia is a rare breast condition that occurs when soft web-like breast tissue pulls breast implants towards each other, until the breasts meet uncomfortably at the center of the chest near the sternum (the body’s midline point). Given this abnormal union, symmastia is known by many other names, including breadloafing, kissing breast implants, and the uniboob.Unfortunately, this condition causes the surrounding skin and pectoral muscles to literally lift off the breast bone as the implants are pulled together. This consequently causes pain and discomfort, as well as obvious distortion of the breasts, which can only be disguised with clothing that does not show cleavage.You should consult with a board certified plastic surgeon for proper assessment. Only after a thorough examination you will get more information and recommendations.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surge

Yes, you do have symmastia.  The correction is replacing the implants under the muscle to recreate the normal medial sternal contour of the breast.