I agree with the others who say to measure in different places and find the average for what your borders would be. Make sure your borders are those measurements. You may have to take in some of the seams a little to get them to fit. I've also basted the edges of a quilt and eased the stitches to make the quilt fit the borders.
And, I also agree that if the quilt is going on the bed and not the wall, no one is going to notice!!!
That is a beautiful quilt!