Pattern negative region

I've created a repeating pattern using a Rectangular Array with the region below (in yellow). To expand the design of the pattern, I'm looking to use the negative "region" (circled in white), that results from the initial region being placed adjacent to itself.

I did a really intensive definition for something similar, and am trying to learn if there is a more efficient way to work with this. Any help is always appreciated, I've attached the definition. Thanks, Michael