She's a beautiful girl Alice13.
My last dog had severe HD and was diagnosed at 4 months with x-rays. Despite her condition she lived a full life, passing just before her 16th birthday.
We managed the disease by limiting running, jumping and other activities that are hard on joints. We kept her lean and fit. She ate like a queen and ran our lives like the shepherd she was. Around 5yrs we started her on Rimadyl and ramped things up as she needed them.
All the while we kept focussing on the positive, enjoying her for the wonderful dog she was. And that is my point. Focus on the now, the positive, what you can do and try not to worry so much about the disease. That is if she even has it. Which she might not. I haven't read your other threads but it seems you already have a pretty good understanding of the symptoms. Keep an eye out for the symptoms as she ages while trying not to worry about them too much.
Dogs and perhaps GSDs in particular (among other breeds) study their humans and read our emotions. Our feelings are an open book to them. If you worry too much and stress about it your dog will pick up on that and stress along with you. I know my Maddie did that. I had to check myself along the way when I started worrying about her disease. It upset her tremendously to see me worry.
Linus van Pelt Haus Juris. My Sweet Babboo, born March 17, 2014.
Madeline Ronan Heart (Maddie) Dec 1997 -- November 22, 2013 Rescue GSD, Sable