Are you using your ruler or your mat to measure? I use the ruler only and make sure my fabric is on the outside of the line. If you just barely measure you're going to be scant. I take the width of the line on the ruler and go to the outside. If this doesn't help cut all your pieces another 1/8" and I think you will be fine. Also sew on the outside of your 1/4" mark for seam allowance..