I like it as is. It's unique and very pretty.

I think it is very pretty but if you are not happy I would go with QuiltnNans suggestion!

Quilting does shrink the fabric. Unequally dense quilting results in unequal shrinking. So increase the quilting.

As to blocking: First off-I do art quilts and they are small enough to fit on the tile floor in the spare bathroom. I do the blocking after the quilting is completed and before binding. It helps remove dirt, marking, threads & animal hair/lint as well as relaxing the fabric and quilting. I fill the bathtub and emmerse the quilt for about 1/2 hour. I lay old towels on the tile floor. The I take the quilt out and squeese (do not wring) out the water. Then roll it in a towel and walk all over it. Then lay it on the towels, patting it into place. I do not try to stretch or shrink, just let it be what it wants with some patting. I put a fan on it so it'll dry in a day and close the doors to keep the cats out-they always like fresh laundry. When it's dry I trim the edges to square it up.

i like it as is it looks quite balanced the the bowing looks like a frame

I really like the pattern. Sorry you are having trouble with the quilting.

I'd go ahead and finish it. It looks beautiful and the slight distortion might be related to whether the fabric was cut on grain or cross grain. Next one you make, confirm that any pieces on the edges are cut "on grain."

I have made several wall hangings and found that dense quilting does cause the problem you are experiencing.
I now do what I call, my anchor quilting around the sections before I do more dense quilting within the "anchored" blocks, squares, rectangles in the quilt. When you outline these sections ( I do start from the center out), then I can go back and quilt "as desired" as they say, within each framed section.This framing of the sections keeps the fabric from drawing up so much when I do the additional quilting. Afraid I'm not very good at explaining....

Two things come to mind: If the binding is already sewn on, does it need to come off if you are only going to quilt the borders? It does occur to me that the quilt might not be square and that might cause the wonkiness, but it also may be that, as others have suggested, the uneven quilting is causing the strange shape. Also, the advice to dampen the hanging and pin it securely to the carpet and let it dry might just stretch it into shape.

I recently had the same problem. I added quilting to the borders and it rectified the problem. I have since learned that scale is very important with fmqing..

It looks to me like the centr panel should have been squared before the borders were added. Don't know if there's anything you can do about it now. I agree with the others who say leave it alone, and just be aware on th next one.