I usually do a light warm up, a heavy warm up and then go right to the heaviest weight I can do for the desired rep range. This way you don't spend energy and sets needlessly on higher rep working sets. You will have the best set (usually) on your first working set before any muscle fatigue has set in. This enables you to lift more weight for more reps on your first set = more growth.
I think u r overtraining also.