A "Rottie group" isn't necessary, just an experienced dog trainer or behaviorist, ideally with experience with Rotties. Vets might be able to refer, good pet supply stores (probably not the big box stores) might have info.
Julie-- have you contacted this group
Butler Dog Training Association - Welcome
to see if they know of someone who could evaluate your girl for you? I don't know anything about them... I just googled "Dog behaviorist trainer Butler PA" there's other links under that search as well, if you want to try it.