Can veneers give me better lip support and fuller smile?

Without photos it's pretty hard to determine if veneers would give you the results that you desire. Remember, veneers are thin so while it may be possible to design them to push your lips out slightly, you shouldn't rely on veneers to make major improvements to your lips. Porcelain veneers may not make major improvements to your upper lip, but they can close your spaces and give you a broader, more beautiful smile. I hope this helps. Click save on the save button below my name, so that you may ask me more questions in the future.  

A photo would be helpful, but I'll give you my generic answer. Like many people, you had bicuspid extractions prior to braces. Thankfully, that's not something we typically do anymore. Because of that, you don't have the proper lip support due to your upper teeth being retracted (pulled in). Unfortunately, veneers cannot provide you with the lip support you are looking for. They would need to be very thick and that would not be healthy or be a good dental appearance. Veneers, or bonding can close spaces, if you wanted to go that route. I hope this helps!