It sounds as though you have several things going on. First of all though if you did not get any better sleep than stage one sleep on your psg, the mslt was basically worthless. The primary reason for conducting a psg prior to mslt is to assess the QUALITY of sleep overnight, along with checking for other disorders which may mimic narcolepsy, stage one sleep is basically no sleep at all so naturally you will be extremely tired and sleep on the following day.
You may very well have a circadian disorder or others which keep you from transitioning to the deeper more restorative stages of sleep.Without the technical data on your study it would merely be a guess.
I will send the name of a physician to your email, although she is in Atlanta if that is OK