I've recently started krav and my studio gave me a boil-and-bite mouth guard that is WAY too big for my apparently tiny mouth. I trimmed the ends so it doesn't make me gag, but it's still too tall, especially the inner walls. I can barely close my mouth and the guard's inner walls dig into the roof of my mouth.
My question is whether I should just boil it and assume the inner walls once softened will sort of bow inward to curve towards the center of the roof of my mouth and run alongside it instead of just digging into it, or if I should trim the inner walls so they don't come up as high into the roof? I'm afraid that if I try either one and it's not the correct approach I'll have ruined the mouth guard.
I've been trawling Google for help but all the sizing advice I can seem to find is people talking about trimming the ends, not the walls, and a bunch of results related to ill-fitting night guards for people with dental problems.