Not a fun solution but usually works is to rip some of the seams to make the smallest blocks a bit larger after resewing them. I have done this many times. To make accurate seams next time..be to measure seams often. It helps to put a piece of tape along on the needleplate at 1/4 inch from the needle. White tape is easy to see. Sew a seam and then measure it to make sure it is the correct width. If not ..Rip and do it over.