I am not overweight but my cheeks say otherwise. What procedure can I have to fix this? (photo)

I am embarrassed about my smile and I cover my mouth or look away when I laugh because my cheeks are quite fat and even though I'm at my ideal weight, they make me look obese and you can't see my cheekbones. When I relax my face i often get asked if i'm upset because my facial expression look sad. I've tried Botox along my jawline to stop the sag I have but now I'm thinking it's my cheeks that are causing a chubby smile. What procedure can I have to fix this and make my cheekbones come out of hiding?