Hello Susan,
I have now finished researching my German relatives. I speak and read German fairly well. I am one quarter German and I may be able to help.
You also have a reply from Betty - she lives in Germany and may be able to help more as she is in the country.
For like-minded people, the Anglo German Family History Society is very good - I was a member for some time and they send you an english monthly bulletin. They also have information lists that you can consult - this was mentioned by nanny Jim below too.
If you cannot find information online, you could contact the Town Hall of Hannover. This is because BMD are held where the person lived.
Here is another link to try:
https://www.familysearch.org/wiki/en/Hannover_Online_Genealogy_Recordsgood luck with your research
Ken