Don't despair!! I did something similar to this a year ago. I was cutting out strips for a class I was going to and my husband said, "are you sure those are the right size". He NEVER says that to me. I measured, and they were not right. I had cut them 2.5" instead of the 2.75" they needed to be! I got some similar fabric and recut the 'mistakes' and cut the rest correctly. Now a year later, I have used almost all of the 2.5" strips in other quilts. I didn't throw any of it away and I'm glad of it.