Where do German Shepherds live?
German Shepherds don't live much beyond that typically.
If life is getting hard for her, you still have a couple of options before letting her go. It is possible she has any one or several of the age related problems: arthritis, heart disease, cancer and she may just not have the vigor to get up anymore.
Hospice is an option for many pet owners, who have a hard time deciding when to end the pain. If each day contains some joy, then life is still good. If you speak with your vet about her end of life issues, he or she may prescribe you a general purpose pain reliever. There are several that are stronger than aspirin, but not as mind zapping as, say, oxycodon.
Your vet can offer treatment to ease the pain, while not actually trying to "cure" the dog. Getting you info on pet nutrition, things you can do like massage to make her transition from life to death less harsh.
You may still have some time left, who knows, with pain management, she may feel more up to getting around. In this end of life stage, she could last weeks, months or even years.