Did you ever have the definititive test for Addison's or were you started on treatment just based on symptoms? I was not diagnosed in the hospital as many are but that was because I suspected I had and asked to get tested on an outpatient basis (not the way it is usually done). If you didn't have a definitive test, then I would say find an endocrinologist who will do it from their office (a lab will need to be close by). If I only took 5 mg/day it would not be enough. If I forgot my meds, by 10-11 am I can already feel my blood pressure going down.
If you do have Addison's, perhaps you still have some adrenal reserve.