Welcome to the forums!
Sounds like you are too worried about how high you are pushing the bar. In the bench, setup with retracted shoulder blades and hold this position the entire set. When pressing the rep up to lockout, thing about wedging yourself between the bench and the bar in order to push the two apart. Almost like moving a heavy piece of furniture away from a wall. Don't overreach at the top of the rep. The rep is done when the bar is over the shoulder joint, elbows locked in extension, and scapulae retracted.
Just to be sure, upload a vid of your bench with some basic training stats and we can give you better feedback.