i am late too but maybe more people with Celiac Disease from the US want to travel to germany so i want to give you some more information. My Wife got her dignosis in 2008 and for now 5 years we are very familiar with celiac Disease.
As stated before meanwhile there are many shops, so called "supermarkets" which sell glutenfree Products:
The biggest and nationwide are:
You get packed bread and cake for Travelling. Some products have to be baked before you can eat it.
Even in so called Discounters you get packed products with the gluten free sign (Gluten Frei) or the Text on it. (Mostly on the back of the product)
Just look for these Shops:
Even the restaurants get more celiac friendly in germany.
On the Site www.glutenfreeroads.com you may search on Shops and Restaurants which had a officially certificate. But always please ask what meals are glutenfree.
Besides this officially tested there are a lot more Restaurants spread over Germany.
We have founded a Facebook Group "Zöliakie Austuasch" with up to now 1100 people in it who share Tipps for Traveling and Eating Outside. Although this group is mainly german we answer english questions too.