My first recommendation would have been clear braces. However, you have indicated that you have already explored that option and that you are not a good candidate for orthodontics.
Yours appears to be a narrow upper and lower jaw situation. From your photos, it looks as though your back teeth are properly aligned, ie, straight up and down, not pointing inward, and that your bite fits well. In which case, you can rule out clear braces as an option.
Porcelain veneers is your best solution for a broader smile. I would recommend that the dentist you select do a “chair-side mock-up”. This is a “test” to see how far back you need veneers to get the smile you want. With this technique, you can also determine how far out you can build your smile with porcelain veneers. Having done this literally with hundreds of my patients, patient goals are not only realistic, but we provide information to my master ceramist so that he knows how to form the final porcelain veneers.