Maybe re-cut it to the shortest width you accidentally cut. Then, adjust the pattern accordingly (if it calls for all 3 1/2" strips, then cut all the others the "new" width depending on what you ended up with.....if it's 3 1/4", then cut them all to 3 1/4". I'm not sure what you used, but I really rely on the June Tailor Shape Cut and the June Tailor Shape Cut Pro. It's hard for me to keep consistent with the width of long strips if I don't use them. Good luck.....you might just have to get creative by adding borders to the quilt to make it bigger once you are done. But, fabric isn't wasted....you will figure out a way.