If your size and strength gains have stalled out, it's because you made things too complex. It's time to get back to basics and get strong... using only 4 reps.
Successful overhead pressers lift with violence and hate. Here's all the technique cues you need to add to that aggression, plus a complete overhead press program.
To build up your squat, ignore things you're good at and spend time doing things that make you downright uncomfortable.