I would get a copy of your tests. It is so hard to tell without a range and every lab and country differs.
Get copies and post back.
That seems low to me, definitely! My endo always encourages me to test cortisol between 7 and 8 am. Most people say 8 am. So yes, it seems pretty low, but a lot of endos don't notice or care. Point it out to them and ask if you could get further tests as you suspect it might be related to your symptoms! (if that is the case) and if they don't listen, go get a different opinion. Good luck, hope it works out!!