Honestly man, you’re exactly like I used to be. Stop thinking so much. Seriously, you’re what, 15?
Go out on a field some day and get good and loose. Have somebody hit some easy grounders to you in the outfield, and just concentrate on fielding them and throwing the absolute crap out of the ball towards the plate. Do that a few times, then take it to the mound. Replicate that feeling in your delivery. Bingo, that’s how you need to throw. Get to where you can repeat that delivery exactly every time you throw, then you can start trying to fix what flaws you might have.
What I’ve found is that if you’re out there thinking about, “Ok, turn the back foot over, extend the posting leg, hips before shoulders,” you’re gonna be robotic, mechanical, and slow. Chances are, if you just get out there and throw hard like your body wants to, you’re mechanics’ll be halfway decent.
I used to be exactly like you are. You’re looking for that one “magic” mechanical move that’ll turn you into Roger Clemens. As a guy who’s been there, let me tell ya: Ain’t gonna happen. Find how YOUR BODY needs to throw, and stick with it.