How about Leah Day's Spiral Knots FMQ? I just used it on a "Thinking Outside the Block" quilt (binding tomorrow, pictures to follow). Your quilt has the circle motif in the fabric and this would duplicate that. It would also soften the lines of the quilt. Here is the link to her site:
http://freemotionquilting.blogspot.c...ral-knots.html. You did a beautiful job.