Uneven results 11 months dual plane via inframammary crease - what's the issue? (Photos)

I am 11 mos PO from breast augmentation (dual plane via inframammary crease). I noticed around the 2-3 month mark that they were starting to look uneven. My right breast is soft, and has a nice slope. My left breast feels tighter, rides a little higher, is fuller at the top, and is firmer to the point where I can actually feel the implant with my hand sometimes. When I lay on my stomach, the firmer breast does soften for a short time. What could the issue be?