Front teeth too big - can a dentist reshape them or would veneers be the solution? (Photo)

Since you’ve already have porcelain crowns on your front teeth, you can not place a veneer on those teeth because those teeth were already contoured and shaven down. A new crown will need to be used to replace an old crown. New crowns can be shorter to get you that more desirable smile design. 

You already have a beautiful smile but I see what you mean about the teeth seeming too large for your mouth/face. Since your teeth already look pretty straight - I would suggest 6 minimal prep veneers on the upper arch. A well-versed cosmetic dentist will use something called the "golden proportions" to get the teeth perfectly sized and shaped for your face and smile. I hope this helps. Good luck with you journey!