Is there actually a market?

I would definitely encourage you to write some stories in German if you are most comfortable with your language. I speak German and am willing to give feedback if you like. I don't know if they'll accept it on this site, though, and your audience will be smaller than if you write in English. MMSA has a vibrant German language sub community but they only accept M/m or F/m pairings. Otherwise your best bet is probably publishing your stories on your own blog (e.g. Wordpress).