Television shows such as "Extreme Makeover" The Swan, and Doctor 90210, have created a large demand for cosmetic dentistry. The doctors and the dentist on these shows are an elite group of highly trained professionals that are able to create what was once considered impossible.
A highly trained and accomplished dentist is capable of incorporating a whole host of dental procedures in conjunction with artistic perception to produce that perfect smile. Unfortunately not all dentists that try their hand at large scale cosmetic cases posses the training and or the artistic perception required to deliver the smile the patient desires.
I can empathize with your situation. Porcelain veneers are considered to be permanent restorations, with aesthetics and strength similar to that of natural teeth. Veneers placed properly, should last between 7 to 15 years, barring trauma.
You stated your veneers were done to straighten your teeth. To assure the best result this procedure requires a suitably trained cosmetic dentist in close concert with the dental laboratory; together they create your new smile in the form of a wax model. The method I prefer is to create your new smile [temporally] with tooth colored plastic over your natural teeth. With this method the patient has the advantage of seeing their new smile in their mouth. Both of the above procedures allow you to see what your new smile will look like before the dentist starts reducing your natural teeth. If changes are to be made it is relatively easy at this point in the procedures.
Your dentist may have used the "prep and pray" technique. Utilizing this technique, the dentist prepares the teeth and then allows the lab technician to create the veneers without a clear plan on what the final smile should look like. This is very risky and lends itself to a lot of surprises!
A properly trained cosmetic dentist will carefully plan for the final result. There should never be surprises when veneers are placed. When veneers are properly prepared, the temporaries should be very close in shape and size to the final veneers. If necessary, the temporaries can be altered. The laboratory is notified of the changes, so they can be incorporated into the permanent veneers.
It sounds like your dentist lacked the proper training and or aesthetic vision needed to accomplish the desired result. Properly done, a veneer case should look great, feel great, and last a number of years.
Better smiles for all.