Push shots are caused by a swing that is too shallow and from the inside, many times caused by the body moving in front of the ball during the downswing and causing the club to get stuck behind the body
Hitting the ball with the bottom of the club face can result from several different swing faults
A common mistake on the backswing is to hinge instead of cock your wrists, a perfect drill to help fix this is to pre set your backswing by cocking your wrists right up in front of your face at address and then turning into a full backswing