Chrystie, if you are following the directions I wrote in the Month 9 blog, I don't know why your roof halves are not coming out 6.5" unfinished. There are only 3 things we can do wrong in piecing: the cutting, the sewing and/or the pressing. Double check that your printed roof templates are the correct size--the dashed line at the bottom of Template B is 6"--this is the sewing line. The 1/4" seam allowance has been added--be sure you include it in your template. If the template is the correct size, and you've cut the pieces accurately, that means your sewing must be off a bit. Double check that you are sewing an accurate 1/4" seam. An easy way to do this is to cut 4 rectangles, 1.5" x 4.5". Sew them together on the long seam, press carefully and the block should be exactly 4.5" square unfinished. If it is wider than that, your seams are too skinny, if it is narrower than that, your seams are too fat. With the Barn Roof angle, you have to get that seam allowance just right on all of the seams, two seams per half, one center seam--for a 6.5" half Roof. Once you have two accurate roof halves, the final center seam is just as important--the roof should be 6.5" x 12.5" unfinished.
Here is that blog post:
bbquiltmaker.blogspot.com/2018/09/month-9-patchwork-barn-part-1-barn.html