I'd be more inclined to look more towards multiple system dysfunction, rather than an isolated gland.
Anabolic steroids disrupts several enzymatic pathways, such as the P450- cholesterol side-chain cleavage. This causes a decline in our endogenous steroidogenic capacity; e.g, pregnenolone, progesterone, 17-hydroxypregnenolone, dehydroepiandrosterone, 5-androstene-3 beta, 17 beta-diol and 17-hydroxyprogesterone. Ultimately, causing disruption to further downstream hormones, such corticosteroids and mineralocorticoids.
A few of the aforementioned hormones further metabolize to neurohormones, such as allopregnenlone. In short, allopregnenlone is a "feel good hormone", if you will.
I personally would look at supporting my pregnenolone and progesterone hormones. Then thyriod hormones, if needed. I'd pull a full thyroid panel, if you so choose.
hCG and pregnanolone can help support the aforementioned.
As for 12.5 mcgs of T3. That's fine, several Anti-aging clinics will Rx that dose, even 5mcgs a couple of times per day. I personally take 25mg of levothyroxine (T4) at bed time and 5mcgs of liothyronine (T3) twice a day. Both are Rx'd.