Thank you all for your suggestions they were all great ideas. I decided to tough it out and make one more block which meant making a strip set - not the end of the world. It's not the same line up so hopefully no one will notice. I decided to do that because of the alternate pattern I had going with the red pinwheels... I did really toy with the idea of a center block or using the 4 extras as the corners for the borders.
Now for the border. I think I am going to do a narrow border in the dark blue/green dotted fabric. Then a wider white border with mini pinwheels cascading across and down the sides and top. How does that sound? (I know like a lot more work)