I don't see it, but if you don't like the way it is, then by all means change it. As mentioned, you can put 4 like fabrics so they come together in the center. Either the green or the focus would work in the center.
Many people do not do the entire hop---I would guess most don't. Do you want to add more because you want it bigger than what you will get with the blocks you have? I ask because I know of people that do from lap size on up. Some only get enough for a wall hanging. I got one block!! I had forgot but went to my LQS and ended up getting a block. We thought of going up to longview or so and getting a few, but didn't. I don't have a clue what I will do with it. Probably a small wall hanging to hang by my machine. LOL.
By the way, did you have fun? My sis and I did it in 2008 and had a blast. When we started we were only going to a few--up to Tacoma. We ended up going to every shop!! Each night she called her hubby and said we're going to be another day.