This just breaks my heart. Your DD's interests sound so much like my DD10's interests. I wish I could just send my DD over to have lunch with yours. Really, just having an additional supportive friend or two might make your DD feel better about being herself. Does your older DD know of any girls in her grade who might have similar interests? Surely the teachers or AIG teacher would have some leads here?
My DD IS VERY lucky that she has always found at least a couple of friends who share at least some of her unique interests. I hope that your DD finds her "people" very soon.