Joy,
When you sewed the borders on did you match the middle of the border to the middle of the quilt body? i have learned, the hard way, that you can't just put the border onto the body of the quilt and sew it down. It's never going to be right.
I measure the borders so they are the same length as the quilt body is through the middle. Then divide the border into 4ths and the same with the quilt body. Match the divisions and then sew. Things will work out much better. There seems to be slight variations of the lengths and by pinning the quilt in fourths you can spread out the difference evenly.
I would recommend that you rip out the seams on the first two borders and start again. You'll be happier in the long run. Trust me, I know!