technique and patella tendonitis. When my legs work, my push press looks easy. When they don't, some day the small dip is a killer on my knees, it looks like I dip then come back up but do not connect the press at all, so its near on strict lol.
I can't do a double dip to get back under as that would be a 2nd small dip putting pressure on my knees.
What I find works the best is lots of lower weight warmup stuff, but then too much takes it out of me for when trying to go heavier.
Tricep wise I'm getting strong enough to be able to press out 125-130kg should I actually get it above my head to the point my tri's kick in. It's just getting it there that is the problem.
So yeah, technique, technique, technique is what would make it better.
Confidence definitely has a part in it too. With a squat or a dead you can bail the lift pretty easy without much fear of hurting yourself. Over head though, its a bloody big weight over your head that can cause you lots of problems lol. That will be sorted with just keeping progressing though
Oh, also once I pass 110kg I need to start continental cleaning the bar up, that takes a lot out of me which again impacts the energy to press. I'm combatting that by doing overly heavy cleans to get my body used to cleaning 120/130kg so that when the time comes to try and press it I'll still have plenty of energy