Is my 5 year old German Shepherd too old to have a litter? is there danger to her health if I don't get her fixed?

With intact females of any age, there is always a risk of pyometra. I've read statistics that there is a 25% chance of intact females getting pyometra by age 10 if they are not spayed. There are risks associated with spaying as well. Personally, I haven't ever bred a dog of that age for a first litter. I always suggest finding a reproduction specialist for older females that haven't been bred before to have a thorough exam, bloodwork, etc. I would also make sure you have all health testing done first, hip and elbow OFA films, genetic testing for DM and other German Shepherd specific diseases, etc... I leave it up to my repro vets to tell me what they think as far as risk vs reward in breeding a female for the first time over the age of 5.

I would first do all the health testing and xrays, if she doesn't have good results there then it will save you a lot of time and money pursuing the breeding exams and I'd probably get her spayed at some point while her overall health is good enough to withstand surgery.