I like the scrappy look, but sadly can't think of any way you can get around piecing it unless you did use the fusible grid, which is very thin, unlike batting. Can you get the fabric off the batting without ruining the fabric?
Maybe some of the folks on the board that have years of quilting experience and more creative can come up with other solutions for you.
Don't let this discourage you. It is a learning experience and you won't forget the piecing step again ;) In the bigger picture of things, making mistakes when learning new techniques is to be expected, the important thing is learning from them.