Your dilemma illustrates just why all quilters need to learn to draft their blocks/patterns. Then, no matter what size you want your finished block to be, you can do it by drafting the pattern, cutting it apart and adding 1/4" on all sides of the pattern pieces, and making a trial block. I know it takes time, but I learned to draft in my first quilting class and I am so grateful to my teacher for having us learn that skill.