Morning cortisol levels are low and have symptoms. however, last test it was at the lowest end of the scale exactly - so dr said it was normal.. would you interpret am cortisol level of 138 (range used 138 -635) as normal?

You don't mention what symptoms you experience. I think your morning cortisol level is low raising the concern of adrenal insufficiency. I recommend consulting an endocrinologist to properly work you up, make an accurate diagnosis and, if indicated,render appropriate treatment.

Lowish. Would repeat. And do saliva testing for cortisol. At 11 PM.