When you're first starting out weight training, the body goes through a lot of neuromuscular changes, therefore, you don't need to change up your routines very much.
But after a while u need to change things up, in order to build muscle, u need to cycle (aka: periodization Principle) Your workouts should be chaned every 4-8 weeks.
You rbody is extremely adaptive, so you need to keep challanging it.
Routine will only work for a short period of time before your body adapts and progress stops,
Changing to a new training regimen that your body isn't accustomed to is the only way to keep progress going.
So, assuming your diet, intensity, and technique are good, your not seeing results most likely because of the frequency in which you change your routine.
Your body can actually go into "maintance mod"
So you will reach a plateau.
So I think that's your main problem here Brother, just change up the routine/intensity/ techniques & you will start seeing better results
examples go lighter on the weight high intensity 1 or 2 set 30 reps each look into my primo log.