I agree with you on how only upper six teeth shows when you smile. This is because of arch being narrow and the veneers were only done for six teeth. This will remain a problem even after you get them redone unless you add one or better yet, two teeth on each side (total of eight or ten). It is hard to comment on the current veneers without seeing how your teeth looked before they were done, what kind of material was used and how the preparation of the teeth was done to achieve these results. Hope you find these points useful if you consider getting them retreated.
Due to misalignment of your teeth, bonding will not give you good aesthetic results unless you get more teeth done, which will not be conservative approach. Orthodontics, possible Invisalign will be the best choice.
Thanks for the photo. The gap you have is very small, but I can imagine how bothersome this could be. I see that you do not want braces, but Orthodontic treatment is your best bet. Are you open to Invisalign (clear removable aligners)? Invisalign can fix this fairly quick. With good retention program-post treatment, you can have and reatin this closed without any trouble. Non-orthodontic options can be bondings or veneers, you want to consult good cosmetic dentist in your area if you are leaning towards those options.
You are right, gap between your front two teeth is too large for the bonding to look natural. Bonding will make your teeth appear more `wider' then `longer' -quite opposite to what you want to see. Pictures you have posted do not show full arch, (Invisalign-not sure if it will work) or braces will be the best choice to close these gaps. I suggest you work with a cosmetic dentist who can also work with a good orthodontist to make this work.
Braces all the way- go with your first option. Get your deep bite corrected and arches widened prior to any cosmetic treatment. Good Luck!