I'm liking it just the way you are doing it, Toogie. I think it will be lovely when you are done.
If I see what is concerning you, I think the inner dividers may be just a tad darker in value than what you used for the framing squares -- I like it that way. But you might try laying over some of the fabrics you used for the outer borders in the middle to see if you like it better, or maybe use some of those middle fabrics around some of the larger blocks to further balance the fabrics.