I see it. Hmmm....
First, when you have busy fabrics in the border, just do a straight border. No one is ever going to notice that you worked so hard! Save that effort for when it will show.
If you measured before you sewed, make sure you use lots of pins. I mark, with pins, where the middle and quarter points are on both the base of the quilt and on the border. I put the base of the quilt with the border and match up the pins. I add more pins in between. If there is some fullness in either the base or the border I try to keep it where it is - don't move the fullness somewhere else.
Now, if all that didn't work, I'm going to swear you to secrecy:
Try starch, sizing or Best Press. Soak the offending area, and use an iron to press it into submission.
After that, you'll want to 'quilt to death' that border. It will suck up extra fabric and keep it where you want it. Piano keys and bead board (piano key with two line about 1/4" away from each other) also help suck up extra fabric and look great on busy fabrics. If you try to do just a little bit of quilting, it will look lumpy after it is washed, so quilt it down!
Once you're done, the quilt will look great. Make sure you let us know if these tricks work for you, and SHHHHH!!!!
HTH!!