Widening your smile after having veneers placed is certainly not a problem. However, if spaces are created between your veneers, it may required to have one or more of them redone. I recommend talking to your dentist about this, so that you and your doctor will have no surprises....
Sorry to hear that you are having such a time with the veneers that were placed by your dentist. It is unclear whether you are having a true allergic reaction or not, but my best advice to you is to return to your dentist and have your mouth evaluated with some non-latex or powder-free...
Though my office is located in America, I can tell you that the smartest thing that you can do in selecting your dentist that will place your veneers, is to research your dentist by thoroughly reviewing the before and after photos of patients that have had veneers placed by the dentist that you...