Were these done fasting, with no caffeine/cigarettes? (I know where we are, but still, one never assumes). If not, they need to be redone. Eating increases cortisol.
Try to have them done prior to 9 AM; otherwise they'll start to drop. The nmol ranges I have seen typically end at 690, so you are actually a little low (which may be due to the time of day), very much so if you ate prior to. It would be best, though, if you could get a mulligan and do it as early as possible.
Make sure they are doing a free cortisol, not a total. Binding makes a big difference.
(Keep in mind, this is solely what I've learned with my little adrenal issues! I'm not a doc, nor do I pretend to be)
Chief cook & bottle washer for one kid, a dog, 6 hens, 2 surprise! roosters, two horses, and a random 'herd' of quail.
~The ultimate ignorance is the rejection of something one knows nothing about and refuses to investigate~