Tisha, your story about your mother and your great grandmother's quilts is so touching! Such a sad thing to have happen. What you are trying to do is beautiful.
You said that your great grandmother's quilt was queen size and that you wanted to duplicate the quilting as much as possible. I would suggest that since this is such a large undertaking, that you create a much smaller quilt? I can't help with any other advice, but wanted to offer encouragement. You have done a marvelous job so far in picking fabrics that are very much in keeping with the original quilt.