ACTH is a very fussy fussy test - so if you did not get a chilled tube and a tech that spun it immediately and froze it promptly, it can be low just from being binned. Lousy handling makes it degrade (and that is just a matter of minutes) and it is hard to judge.
So, it is hard to tell - was it done correctly? As well, a low ACTH can indicate the problem is pituitary, not adrenal.
If the cortisol was done at 2 pm, it is not perfect - it really should be 8am, fasting. So you are supposed to be lowering.
One test does not tell the doc much anyway.
I am not convinced adderall causes AI. AI is a salt wasting disease. Addison's can be auto-immune, or it can be pituitary - or from steroid use... but I have not known it from adderall. But I don't follow the whole *fatigue* school - only the real disease.
The reason i think i have addisons is because i had a problem with my acth and my symptoms.
super dark brown hyper pigmentation, Chronic fatigue syndrome, weakness, anxiety, i feel better at night, personality change, losing weight... i weigh 95lbs now, but the lowest was 79lbs and im 22 years old....and many more symptoms. The tanning part is why i think its addisons. i've never tanned in my life and im extremely dark and i haven't seen the sun in like two years.
With that hyperpigmentation, then for sure the lab did not handle the ACTH correctly as it is way too low to cause that. Keep in mind other things can cause darkening skin - diabetes is one. Only elevated ACTH causes the tan - mine is near 4000 - and I got dirty knuckles, tan, spots and all sorts of ugly looking stuff all over. I had to take dex to suppress it but I still have a light tan.
Did they test sodium and potassium or renin/aldosterone? That would be a huge hint to the doctor.
There are a LOT of tests to be done - plus it could be other issues. But with your symptoms, your doc should take you seriously.