What options for one cheek being bigger than the other? (photos)

Since you have established that the left cheek is the good one and the right one is too big, then right cheek reduction can be done,. The question is whether this is a bone issue  or one of just soft tissue. That answer is important since it would help determine what procedure to do and how effective it might be. I would recommend getting a 3D CT scan to see if the bone is the source of your asymmetry, then an intraoral bony reduction can be done.

When patients have an asymmetrical cheek and one cheek is flatter than the other, a one sided, unilateral cheek implant can be placed on the flat slide to accomplish symmetry in the face and match the opposite cheek. Cheek implants are inserted through an intra-oral approach under local or general anesthesia as an outpatient surgical procedure. For many examples, please see the link below