So, after a little research

It appears that my little mystery chick may be a Dominique. The chicks at that address look nearly identical to the one in question, with white spots on the back of the head, white belly, wings beginning to bar, and a comb that is not the single that most breeds have. He/she even had a little black running down the front of the legs when they first arrived. As for the size, there are bantam Dominiques, but none listed at McMurray - the place that I bought them from. The Dominique seems like a very interesting breed - one of the first (if not the first) developed in America. They are also said to be very personable and calm. Here's hoping that it's a pullet so she can stick around.