You've got to hang in there. It's not you. It's the economy. Don't take any rejection personally.
Even though I'm not applying for a bilingual job, I too am having a hard time finding full time work. I was laid off in July 2012 and I'm still looking. Like you, I've had a handful of interviews, but nothing that led to an offer. not yet. It really is frustrating and some days, it's hard not to get depressed.
We both need to keep plugging along. We both need to stay positive to the best of our abilities. For now, while you look for full time work, could you take a part time job for some supplemental income ? That would be something to do while you look for full time work. And having something to do even part time would help pick up your spirits.
Also, do they have recruiting agencies in Germany ? If so, look into recruiting agencies. It can't hurt.