First, the quilt is on its way to awsome! the dog ear thing is not a problem. I would simply push a pin straight though the seam where the two fabrics intersect. Leave that pin in place and secure pins on both sides of the seam to hold them in place. then remove the pin that held the seam points together.
Others on the QB probably have better instructions then I do.
love the fabric you used for this beauty!
peace