Could you get up enough gumption to just do straight line quilting in a grid pattern - even diamond grid? I know exactly how you feel about not wanting to ruin the top. I made top after top and was too afraid to quilt them until a good friend pleaded with me to help her quilt the charity quilts that she had. It was very good practice and of course, i keep getting better with each one that I do. I am not afraid now, and welcome new ideas to improve what I do. Start practising on some practice sandwiches and you should get brave enough to try the nice one.
My friend deliberately made me get out of my comfort zone, and I still do 10mins practice on a sandwich before starting a new quilt, as it loosens me up. All the best with it.