I do calisthenics only.
I see difference in mirror, but I don know whether that progress is the max possible thing my body can do.
I started in October. 183cm 77kg.
I gained 1 kg per month for 3 months. Max weight 82 kg. Then I started cutting. Now I am at 78.6 kg.
In the beginnging, I couldn't do a horizontal push-up, no chin-ups, and no rows on rings.
Today I still cannot do any of it. Not even one single chin-up.
I do this routine: https://www.reddit.com/r/bodyweightfitness/wiki/kb/recommended_routine
People there tell me if I don't progress, then the form is wrong or I don't eat enough.
I gained 1 kg per month. This is a gain.
But I don't think that the form is that relevant. It's ony relevant when you wanna give your best, like for a competition. But I don't think form is that important when you just want bigger muscles. I do chin-ups with a resitance band. That means my muscle work. How can a form matter? Can't imagine.
I totally believe that I have a medical condition. Like low Testo. But supplementing it can be dangerous.