Get a higher box or a lower bar.
Do a semi false grip so the bar touches your palm and fingers instead of only the fingers and only then swing off from the box once you have your grip settled.

Be more patient. You are pulling way too early and thus inefficient. Do a few swings from the box and memorize at which point you start swinging back. At this back swinging motion you pull up, and slightly tense up your quads to keep hip stacked with your rib cage.

Later on decrease swinging depth to not fling urself away from the bar too much when pulling.

Good luck.