Darn bias edges! It looks like the bottom is the worse. Remove the white, measure the quilt center and put a pin in the white at the correct size. Fold the white in half and the quilt bottom in half and put pins in or mark. Pin the ends of the white to the quilt ends. Match up the center pins of the top and the border and pin. Ease in the fabric on both sides of the center pins ( add more pins if necessary) I put the border on the bottom so I came sweep the top towards the needle with a pin or stilleto as I sew. The reason I said to just put a pin in the white border is because I don’t cut off the extra until I am sure I won’t need the extra fabric. A pain in the butt but you can do it. If you end up with a little wave in the border, add lots of quilting to use up some of the extra fabric.