Do you know someone who has been quilting for a long time?? Ask if they will "adopt" you for an afternoon to see if they can figure out where you went wrong. If you still have those blocks can they be trimmed to match the smallest block so you can use them?? Accurate cutting and consistent sewing is important, but you still need to measure the finished blocks to see if they need a trim somewhere. Sounds like you are getting the hang of it but someone to watch how you do things and offer help can be priceless.