The edges are not clear to me, are they pointy?
If you do the backing, flip it right side out thing ... when you get to the points, do a stitch or two straight across the point part ... can't explain how it works, but by doing that, you will end up with a pointier point when you turn the quilt right side out ..
It was a tip I learned from Sew Perfect YEARS ago. I had opportunity to go back to the factory and was sewing collars. My supervisor asked how I had accomplished the good points ... the tip became a factory operation step!