How can I widen my smile and reduce my buccal corridors? (Photo)

I’ve had braces in the past which straightened my teeth (they’ve shifted slightly since). However, I still only have a 6-tooth smile and hope there is a way I can feel happier with how my smile looks. I went to the orthodontist and he said I could get braces (not the most appealing option as an adult) again, but may not see a huge change. I’m 29, so im not sure what could actually lead to a desired outcome. I feel like I have a narrow pallet and hate how large my buccal corridors are.