If diet and drugs are on point, then I would look at your movements and are you stagnating because you are not getting enough stimulation.
If you consider the three main causes for muscle growth, Progressive Overload, Metabolite Overload, Eccentric Tension.
Then look at your training program against these three elements and change the emphasis and balance of your program to put more emphasis on a deficient area.
So if you are doing lots of high intensity low volume, switch for 4-6 weeks to high volume, lower intensity, with pauses through the movement.
You also need to consider if you are taxing your CNS too much and need a deload. Drugs are great at reducing overtraining, but they don't eliminate it.
to get the body to respond to the new