I am an instructor with Impact Zone Golf. I saw this question, and I was eager to answer it. Without seeing your golf swing, I am going to go with the most common problem I see with coming up out of our shot.
One of the most important things we teach here at our golf academy is a 4 inch swing bottom in front of the ball.
To achieve this, we need to use the work horse (lower body) to drive the hands and arms forward of the ball. When we use our right hand alone to hit the ball, we have a tendency to hit behind the ball, or hit up on the ball. That would then cause my left arm to pull up and in, and making me come out of my posture. Not picking my head up like some other people might say to you.