Without seeing you in person and observing how much teeth you show when smiling and when your lips are at rest with your jaws relaxed and slightly separated in the back, it would be difficult to assess if they are too long or not. The length is something cosmetic dentists oftentimes determine when the patient in in their temporary veneers, which for many cosmetic dentists serve as the prototype for the final veneers. However, should you feel they are too long they can oftentimes be shortened by your dentists. Some adjustments in shape and length are frequently done with porcelain veneers and porcelain crowns.Regarding the swelling, it may be that your dentist had to go under your gums a bit more than normal for some reason. Your gums being a little larger may not be a problem unless they are red in color (healthy gums are pink), bleed easily (especially when the dentist checks under the gums with their pocket measuring instrument). Should this be a problem for you then you would most likely need to have a gum specialist adjust the gum attachment under the gums close to the edge of the veneer and bone surrounding the root.I don't believe that any dentist could not determine without actually seeing you is if the veneers didn't fit smoothly under the gums or were too thick.My suggestion....go back to your dentist and see if he has any solutions to the issues you mentioned. It looks like he/she did a nice job, so it might just be a matter of some minor adjustment or smoothing, or possibility there was some residual bonding cement left under the gums at the edge (margin) of the veneers.