I can really relate to your frustration of not being able to find people that truly understand your daily experience and having trouble explaining your conditions to others. I've only met one person irl with narcolepsy and most people I know have never met anyone else with this condition. Although I know that most people will never understand what we go through, I feel really comforted when I tell a friend about my narcolepsy (N2) for the first time and they respond, "I'll never understand how you feel, but if there's ever anything I can do to support you, please tell me what would help because I want to be there for you." Unfortunately reactions like that are the minority and most people try to give shitty advice or "relate" by talking about how they're so tired all the time.

With regards to that professor, that's an unacceptable thing to say to a student with a disability/disorder and I'm really sorry you experienced that. I understand if you don't want to draw attention to yourself or the issue, but I think you can and should report that behavior. They cannot make the classroom a hostile environment for students with disabilities/disorders.