Well done, blepharoplasty is great. However, minor deviations in technique can wreak havoc on eyelid function. Your doctor is letting you that the eyelids are exposing the cornea and are not closing well. Yes repairing this is very specialized. There are a handful of us that fix this type of situations. Generally you will benefit from management of chronic corneal exposure by seeing a board certified ophthalmologist. When you are ready, to need to find an oculoplastic surgeon you offers specialize repair of the eyelids after blepharoplasty.
I have never heard the term fishmouthing in 30 years. Not exactly sure of meaning? You need to protect your dry eyes. Follow this regimen. Cool mist vaporizer at night in sleeping room, drops in day and gel if artificial tear drops do not give relief, Refresh ointment at night and then a wet patch ( saline). Then use large sunglasses when outside and choose glasses with the side visor to protect against wind. See you ophthalmologist about other ideas. If after a full year no better then consider revision possibly. My Best, Dr C