It seems to me like you are almost squatting your knees are bent so much. You may want to have a little less bend in the knees and bend a little more forward at the waste.
If you look at these two images, you'll notice some major problems with your posture. Your spine is bent, slightly, but the bend is there. Your arms are dangerously close to your body, and that is a result of your knees being so bent because you are too close to the ball.
Take a step back and bend at your waist to reach the ball, not at your knees. Check out the difference in angle of knee bend from the left side to your image on the right.
If you look at your posture and you think it looks a little like you are squatting, that is due to your knee bend. If you top the ball a lot, it is probably because you are straightening your knees in your forward swing.
Just my non-expert opinion.
Michael Lamanna is the guy on the left. Used to be a pro at La Cantera in San Antonio where they used to play the Texas Open (Valero). Good guy. I think he's in Phoenix now. He does a lot of the videos on "About.com". I remember hitting balls on his range where that picture was taken and him setting up that clock diagram on the range. Great teacher, imo.