You could ask the bride or her mother for the info.
The mother did say that her daughter PREFERRED pastels so ,if you can't find out any other way, I would add GLIMPSES of a 'pop' color.That's my opinion.
The quilt sounds wonderful. I'm not a pastel person when making quilts but sage and gray are a great combo that I admire in other people's quilts. Don't forget to post a pic of it when finished.