Fix for concave cleavage? (Photo)

Your implants are large and you have little breast tissue to hide the implants. It would have been much better to go with smaller implants behind the muscle. Mesh might be helpful to give a little more tissue in the thin areas. Do not go bigger for this will look worse.

Dear Cool773544,
I understand your concern. However, without a proper assessment, it would be difficult to determine what is wrong. It is best that you visit your plastic surgeon for further assessment or ask for a second opinion. Only after a thorough examination, you can get proper recommendations and advice.
Daniel Barrett, MDCertified, American Board of Plastic SurgeryMember, American Society of Plastic SurgeryMember, American Society of Aesthetic Plastic Surgery

This might require a proper consult/physical exam to determine what the best procedure would be.
I'd be curious to know why you changed to the subfascial plane. You upsized a few CC's but also went to a high profile implant - which is narrower with more projection. This tends to be less optimal for cleavage.
If they're sitting too lateral - a pocket repair could help improve the cleavage. But it also seems like you're seeing too much implant in the cleavage. Fat transfer could help but I would need to see you in person to determine that. Or going back to a moderate profile implant, which might give you less of that steep transition to the cleavage line.