Keep trying what ever method you use. I use to use the 2.5 binding and .25 seam but I was always left with empty binding. I cut my binding size to 2.25 with .25 seam and stitch on the front, hand sew to back and make mitered corners. I always have to use the sheet I saved for mitered corners cause I forget. I still have not gotten the sewing the ends of the binding together with a bias seam right. I have been doing bindings for about 20 years now. Ok so I am a slow learner lol . Give yourself time and practice.