I never use bias or straight of grain binding strips. I use 2-1/2" strips, cut width of fabric, Fold in half and press, joined on the diagonal and usually round my corners, I pull the binding kind of tight when I sew onto the front, then hand stitch onto the back. I suggest you look this up on here or look in quilting books and try different ways to see what works for you. I have been quilting 45-46 years.