I'm not sure how to answer your question about not making a "perfect match", but one way, other than really learning the math, is to use graph paper. I've drawn out a lot of "uh oh's" on graph paper and been able to figure out how to get things to go together. Just remember to add your quarter inch since you will probably draw your quilt as finished blocks. That's where one of the "add a quarter" rulers comes in handy. I think your quilt is lovely! Way to go, girl!