Night Guard problems

Today I picked up a new night guard from my dentist. I was asked to keep it in my mouth for a bit and see how it fit. When the dentist came in to check it, of course he leaned the chair back and I realized that my upper lip would not close over the upper night guard. This is also what I've experienced with OTC night guards, I was hoping that for over $600, it would have a better fit and that I would be able to close my mouth. When my mouth is held open by these devices, I experience painful dryness under my upper lip, which I cannot just treat with a heavy dose of lip gloss. And I'm sure the dry mouth cannot be healthy for my gums and teeth.

When I asked the dentist about it, he first suggested OTC remedies of which I'm aware, Biotine rinse. And I have to say when he started telling me how I'll need to have veneers done, ruin my teeth, if I don't wear it, I was rather annoyed. Of course I see the value in wearing a night guard, that's why I agreed to buy one.

So please, can someone tell me is it unreasonable to be able close your mouth with a night guard in place? Would a lower night guard present the same problem? I've been told I'm the only person he's had with this problem.

Up to this point, this guy has been, hands down, the best dentist I've ever had. His attitude about this really threw me.