The proportions are a little off, it's a common thing among aspiring artists. You are simply thinking too much when you draw the sketch. The left side of the brain is often dominant in people and it just LOVES to break things down (head, ears, arms, tail, etc..) and this can easily make you loose sense of the overall picture while you work. You want to be able to see the shape of things without knowing what they are. This can be pretty hard to do, and experience is the only way to really achieve it, but there are some little tricks you can do to speed it up. If you have some reference material you are working from try turning it upside down. If you ever notice yourself thinking "Now time to work on the..." STOP, work on something else, but don't fret on it.