Are your teeth actually that bad, or are you getting yourself worked up over nothing? That dentist said they usually don't see that much wear on someone's teeth at this age, but not only was that appointment literally months ago at this point, but even though you weren't wearing this mouth guard most of the time, your teeth still look, feel, and seem way better than other people with bruxism (grinding your teeth) at night. Like, yeah, it's not perfect, and you're still stupid and irresponsible for forgetting your mouth guard so often, but your teeth seem to be fine for now. Have you seen some of these pictures that are posted online by comparison?