Just thought I would bring this back since this "Adrenal Fatigue" thing aka HPA dysfunction thing is real. It is worth getting tests for testosterone, cortisol, LH/FSH, prolactin, TSH, free t3, total/free t4, ACTH. A blood test is fine but saliva test is better for the overall pattern. One can also do a 24 hr urine test or a 4x/day dried urine test (the best). Other things people test are plasma or urine catacholamines--(only reflects "stress" level in terms of how much adrenaline you are making--it cannot be used for any treatment plan really)
However, what most people don't understand is that it is not the adrenals that are directly the problem! Ashwagandha and other adaptogens are good any many naturopathic websites claim that they heal the "adrenals" but no thats not true. In reality, it is a problem with the PVN of the hypothalamus and the low cortisol is simply reflective of signaling problems in the PVN. Adaptogens, 5-HTP, SSRIs, Buspar, L-Dopa, Benzos, gabapentin, etc help to normalize HPA axis function. So no, your dr is not stupid for giving you SSRIs and saying "adrenal fatigue" doesn't exist--the name for it is just really bad. If you have thyroid or sex hormone issues, fixing those will also help normalize HPA axis. So will fixing nutritional deficiencies and decreasing stress/using mindfulness/CBT. You need to find a dr that treats this stuff holistically from every potential angle.
Direct hormonal treatments like hydrocortisone can potentially help but then comes the problem of coming off of them which can be hell since they suppress your adrenal function.
The HPA axis can essentially be thought of as our "mind-body" connection. When its disturbed--your perceptions and everything get thrown off. You may ask, ok then why do people get better w/o meds as if it really was "all in their head." My answer to that is that the mind-body connection is very powerful. By trying to live life normally, you are pushing your axis to react normally in situations and thus it heads towards its baseline pre-LTC state.