I don't know German, but I'm bilingual in Chinese and English, learnt French in high school, and taught English as a second language. All I can say is this -- of course it's taking forever. Languages are incredibly rich and complex systems, with centuries or millennia of history. Rome wasn't built in a day, so why would speaking like a Roman be much different? The only thing you can do is be patient and increase exposure. Watching subbed movies/TV shows in a foreign language is a good way to learn imo.
Chimera of Filth
A gruesome beast with dripping flesh
Clings to me as a sick fixture
My throbbing heart it gnawed apart
It stalks and hunts me through mirrors