When you make a tee shirt quilt, always, always, always cut the tee shirt extra big. I usually cut them at the shoulders and down the sides. I stabilize with a fusible, light weight Pellon. I use about a half yard per tee shirt. Then and only then, cut the tee shirts to the size you want them. Then you can add sashings and what ever else you want to add to make the quilt. I just finished one for my granddaughter for her high school graduation. Use your imagination when pieceing and make them fun. I would love to see pictures of the finished quilt.