Whenever I can, I use leftover fabric from the front to add to the back to resize however I need it resized. If I need to, I just use coordinating. With your two yards you can probably even get binding. dunster is right about how you are going to quilt it ..... makes a difference on how big the back needs to be.
Here is the back of my avatar quilt. I used scraps so I needed less of the gray.
Last edited by Monika; 05-19-2017 at 04:18 PM.