Diagnosing the Push
The grip is not normally a factor with a push.
Make sure you aren't aiming too far to the right of the target line, or that your shoulders are aligned too far to the right.
You might have the ball too far back in the stance. This causes you to make contact when the club is still swinging to right field.
You could be taking the club back too far inside, pulling the club away from the target line. The club should track a gentle arc on the way back, not a rapid arc to the inside of the target line.
The club might be swinging too much to right field at impact. Your right shoulder could be dropping too soon and/or your hips might be sliding toward the target, preventing the club from swinging back around to the left. Make sure your head doesn't move to the right in the downswing.
Video: What causes a push?