Odd question but i feel as though im experiencing low cortisol symptoms and im looking to increase it, getting bloods done soon for post PCT just need to test methods on myself and see if it is infact low cortisol, experimenting for now!
Firstly, to measure cortisol in blood reliably you want both total cortisol and CBG, kind of like total test and SHBG for bioavailable testosterone. The 'free' tests are only useful for T4 and T3 in the realm of most typical blood testing and monitoring. Total cortisol will likely not mirror the cortisol-related symptoms one is experiencing. Salivary cortisol testing, however, would.
Secondly, it is up to you and your doctor how to proceed with increasing cortisol. What has worked for others is MLM pregnenolone pills, made by Nutricology; pregnenolone cream, usually DIY or from a compounding pharmacy; and progesterone cream, widely available OTC for aging women (and men).
Lastly, for any of the above to work, thyroid should be working well. The enzyme conversions pregnenolone > progesterone > cortisol are regulated by T4 and T3 and the conversion from T4 to T3 itself requires cortisol. Also, you can't really "shut yourself down" with pregnenolone as at worst you can end up with high cortisol and hate the infinite energy and great mood it provides even with low testosterone. You can top off your pregnenolone/cortisol unlike your testosterone that gets shut down as soon as anything binding the androgen receptor is introduced. You can have A natural cortisol and add B exogenously and be left with A+B.