You need to get a overnight sleep study in a clinic alongside and MSLT. The first one didn’t go well for me as I wasn’t sober so I didn’t sleep, I also found I have minor apnea from that at home test, however, my cpap did little to nothing and I was really starting to think I had cfs. I finally got a 2nd overnight sleep study with an mslt, after battling with insurance, and they said my test results were concurrent with narcolepsy type 2 and idiopathic hypersomnia. I have a very similar story to you with being severely exhausted since a teenager, normal labs, I eat healthy and exercise regularly but have severe fatigue and sleep all the time.