That's interesting. I have all the same problems as you, and so did my father and several members of his family. I have particular problems with sleep paralysis accompanied by hallucinations of the type you describe in the incident in the dorm, only very much worse in my case. Ditto my father.
I too find it difficult to stay awake during periods when my mind isn't fully engaged. For this reason I've never dared drive. My father was even worse than me - fell asleep twice while riding his bike. I've also had two episodes of cataplexy during my life, which is another symptom of narcolepsy. As you probably know, sudden episodes of completely uncontrollable daytime sleep, sleep paralysis (including false awakenings) and cataplexy are the triad of symptoms required for a narcolepsy diagnosis.
Like you, I was also told it couldn't be narcolepsy, and my father was told the same. We were both told it was hypersomnolence.
I originally trained as a nurse (many years ago!) and specialised in neuro after I got my general qualification. Having had my first terrifying attack of sleep paralysis hallucination during the stressful run-up to my general exams, I was anxious to research this once I got access to the library in the neuro unit in those pre-internet days. What I read was that sleep scientists in those days (the books were written in the 1950/60s) believed that hypersomnolence was closely related to narcolepsy, and was probably a minor version of it.
As far as I can make out from internet research, things have moved on since then and scientists now believe that hypersomnolence (more often called hypersomnia these days) is totally unrelated to narcolepsy, which is a REM sleep disorder. I'm not so sure, however, particularly having heard your story. It wouldn't be the first time sufferers of a particular condition have known far more about it than the scientists researching it!
A grain of hope has now presented itself for me. In the past 25 years I seem to have had increasing problems with sleep apnoea. I have recently convinced my new doctor to refer me to a sleep lab, the previous one having always insisted I couldn't have sleep apnoea because women can't get it! (Doctors, eh...?) Unfortunately, the first appointment I was given coincided with my holiday so I'm now awaiting another one for the autumn. I'm really looking forward to the results of the sleep study, as I have a hunch it might show up some kind of anomaly of REM sleep. That's if I manage to get to sleep, of course. Paradoxically, I've often found it hard to sleep at night, even when I haven't allowed myself to sleep during the day!
So, how does one cope with our problem? With great difficulty sometimes, but it's quite possible. I've never dared drive so have always made sure to live in areas with good public transport. I too can remember falling asleep in lectures, concerts, at the cinema etc., but this has in fact improved a bit with age (though I can still embarrass myself sometimes!) The sleep paralysis episodes come much less frequently with age too, and I've also learned how to cope with the related hallucinations, which can be quite terrifying.
If you're interested, I can send you a private message with the results of the sleep test, but it won't be for quite a few months yet. You can private message me via this site any time you want to. To do that, just click on the envelope icon under the person's avatar. PMs don't reveal the email address or other details of either party.