Sorry to hear you're having such a rough ride with your GP. I can't quite make out from your post whether you actually got to the sleep clinic or not. I'm afraid GPs aren't always very knowledgeable about sleep disorders. I've had every indication of obstructive sleep apnoea for years, but my former (female) GP flatly refused to refer me to a sleep clinic, as she said it was impossible for women to get it. Since a recent house move, I now see a male GP who says that's utter rubbish and has referred me! (Still on waiting list.)
This all ties in with your sleep paralysis. I have this too, together with the associated hallucinations. It's a well-known condition that I've had all my adult life. It tends to be hereditary - my father, at least one of his siblings and their mother all had it.
A small proportion of SP sufferers also have narcolepsy. This is a condition where people fall asleep uncontrollably during the day. However, to get a narcolepsy diagnosis you'd have to have the third leg of the condition - cataplexy. This is where the sufferer abruptly loses all power of movement for brief periods when they're awake. Typically, these people suddenly collapse to the floor when laughing or under the influence of other strong emotions. It doesn't sound to me as if this is what you have, particularly as you say you've had a lot of investigations.
There's another condition called hypersomnia, which affects many SP sufferers. This is excessive daytime sleepiness without cataplexy, and which is less extreme than the daytime sleepiness of narcolepsy. This one is very controversial because of the overlap with narcolepsy. Many doctors refuse to accept it as a condition at all, let alone connect it with SP, whereas the majority of SP sufferers - including myself - report some degree of hypersomnia. (And I know who I'm more inclined to believe!)
I suspect the underlying cause is obstructive sleep apnoea. These days, sleep specialists are far more ready to make a connection between SP and sleep apnoea than they used to be. I'm pretty sure I have it. As well as being told - in the days when I had a bed-mate - that I sometimes stopped breathing for quite long periods, I also sometimes find myself unable to breathe during sleep paralysis. There can be some confusion here. SP paralyses the voluntary muscles that assist our breathing during our waking hours, leaving only the diaphragm functioning. To someone waking in a panic to find themselves paralysed, it can feel as if they can't breathe, as they're unable to take a deep breath using the intercostal muscles. However, experienced SP sufferers are usually able to discern the movement of the diaphragm. This is usually the case when I wake in SP, but on other occasions I am distinctly aware that my soft palate has collapsed into my throat, completely blocking my airway. That's why I'm looking forward to the sleep clinic!
Obstructive sleep apnoea is most common in overweight men over the age of 50, which can lead some doctors to dismiss the symptoms when they occur in women or younger people. It can, however, occur in patients of either sex and all ages and builds. One of the main symptoms is daytime sleepiness, due to sleep disruption.
As to how cope with the hypersomnia - well, it does tend to be something of a life sentence. My father had it too. He twice fell asleep while riding his bike! It's very annoying and exhausting, but you just have to organise your life around it. I've never dared drive, as I know I'd be at risk of falling asleep at the wheel.
Finally, as a former neuro nurse, I'm a bit puzzled about your doctor's assertion that you can't possibly have a sleep disorder as your waking EEG is normal. Things may have moved on since my time, but as far as I'm aware, a normal EEG wouldn't exclude a sleep disorder.
I hope you get your sleep issue sorted out too and good look with the clinic appointment.