1. Dog should be exercised and given purpose...work with the dog on behavior and training, every day. Yes, every fucking day. A tired dog is a happy dog. GSD's are workers, they need to have a purpose.
2. You should do as much as you can to give the dog confidence, if it's a "shadow" dog (always your shadow), work harder on ignoring the dog...let it feel build up some confidence about being alone, without you, even when you're in the house.
3. Start leaving the dog alone (out of the crate), at random times for small periods of time (5 minutes, 10 minutes). Vary where you go, what door you leave from and enter by, and every time make sure the exit and greeting is "no big deal". Dog needs to learn it's routine that you leave, but you always come back. Build up towards longer and longer periods of being alone. When you come back and the dog is good, gentle praise. If she's bad, ignore it and try again.
4. Make the dog look forward to you leaving. Puzzle toy with some treats in it, every time. Frozen wet food in a kong, something that challenges and occupies the dog. Maybe leave some music on, or the TV, and shut the blinds as outside agitation can stir up anxiety.
I've been through it many times, just went through it with my new dog (corgi/shepherd mix) and these things work but they take patience, work, and consistency. It's worth it, tho.