How can I get thinner pancakes?
To make you pancakes spread more, and thus be thinner, increase the amount of liquid in the recipe.  This will make the batter less viscous, so that it will spread more before beginning to set, thus giving you thinner pancakes. 

I would start slowly, perhaps a couple of tablespoons extra milk (or just plain water) until you find the consistency that you like.

You will also have to experiment to determine the appropriate cooking time, as the additional 
liquid will somewhat need to be cooked off to get the best texture.

Of course, there is nothing wrong with using the bottom of your ladle to help the batter spread out a bit more.  This is normal, and will somewhat even out as the pancakes cook.