Crys said:

I'm also kind of not sure you should use your ending statement about not having anything published. It seems kind of amateurish to point that out to an editor. That last paragraph is optional, so if I were you I'd leave it out.

The rule of thumb, as I understand it, mention pertinent previous publications, and if there aren't any leave it out. However, if you have established a platform via another route then that should be mentioned. I am thinking along the lines of a literary blog with a large following.