That is a gorgeous quilt....a beautiful tribute to your friend.
I have a butterfly design that I cut from a magazine and it looks similar to yours. I used it as a quilting stencil on another quilt. The quilt in the magazine was called "Giant Flutterflies Quilt" and it was in "Quick and Easy Quilting", June 1997. See if you have that mag and check it out.
Have a wonderful day.