Again, this is very broad. And it is more complex than you write. For example, excess cortisol would also lead to excessive adrenaline production (cortisol increases the conversion of noradrenaline to adrenaline) which could lead to adrenergic desensitization and noradrenaline depletion. It could also be the reason behind the GABA and serotonin issue. Because if you are constantly amping up the nervous system you constantly rely on sero/GABA to bring it down and it can lead to depletion.
You must find the ONE linchpin cause. The main reason why you are messed up. Not try to attack everything at once. I believe that cortisol is likely the main reason for your problem and mostly the adrenaline production it leads too.
If you don’t first solve the cortisol issue, fixing serotonin and GABA will only be a band-aid.
Rhodiola in the morning (to balance dopamine and serotonin, minimizing excessive conversion of dorpamine into noradrenaline, which would lead to excess adrenaline), phosphatidylserine post-workout and at the end of your work day, glycine post-workout and at the end of the day and magnesium taurate 3x per day would help with the cortisol/adrenaline issue. Z12 at night would help with both serotonin and GABA.