Reb, I will repeat--1\4 inch difference over a distance of 10 inches is hardly anything. Looking at the design, the only place where points MUST meet, is where 4 blocks come together to form that background diamond (or on-point square). Try sewing 4 blocks together. Use a long stitch because this is just a test. See how it goes.
To make your seam width just a tiny bit wider, move your needle a couple of clicks to the left.