Does it look like my masseter muscles are too big or is it my buccal pads?

There are several areas that can make a face look wider than ideal including buccal fat and masster.  Lateral fullness is often masseter related while central fullness can be buccal related.  Best Anil Shah

Buccal fat pads and masseter muscles give fullness to the lower face in two different areas. Buccal fat pads give fullness to the ANTERIOR lower cheekMasseter muscle  give fullness to the POSTERIOR lower cheekJohn Mesa MDNew York City and New Jersey Buccal Fat Removal Specialist.

Buccal fat excision is an appropriate surgical procedure for patients that of overly full and wide cheek areas. In common terms, it is good for patients who have chipmunk cheeks. Liposuction can also be used to further slim the face. In reviewing your pictures, is difficult to tell if you're a good candidate because your cheek area is slightly full but not overly full. You are a patient that would need and in person consultation for a complete evaluation and explanation of the positives and negatives of this procedure in your situation.
I hope this helps.