OMG ... I cannot believe the mistake I have just made. I am so mad at myself! The "border" squares are the wrong size. They are six inch blocks, and they should be nine-inch blocks.
I have two options. Make a bunch more blocks and hope it works out border-wise. Or, do a whole different layout with what I have!
ARGH!!!! The things we do to ourselves!
Before I make more blocks, I am going to see if I can get a new layout that I like!