Your squares are really cute!! I like the idea of the white sashing, but I would probably go with a wider one- like 2 inches, or even the same size as one of the squares in the nine-patch. (I like a lot of white.) Whichever way you do it, it will be cute because your fabric is so pretty.
Your squares made me think of this quilt:
http://redpepperquilts.blogspot.com/...d-project.html
It's kind of the same, but uses "reverse" blocks, too.