German social event which helps you to get some friends
I'm not a german fellow, but I have a netizen friend who feels incredibly anxious and wasn't able to get friends in school, due to immense bullyings. They only have friends from the internet, and they have tried to socialize in a fishbowl event but they weren't able to get a friend there as I feel it.
In my country there is an event organization called havervagy, which has a bunch of events, where everyone is spliited into 3-4 people sized groups where they can get to know eachother. Do you perhaps have something similar to this one in Germany? My friend lives in West Germany, closer to the border of Netherlands.
I'm not sure what to recommend. Usually that's a time when you re-align your values and are dropped into a new world with different responsibilities. Around 18 you've finished school and now start an apprenticeship or you go to university and inevitably meet a lot of new people there. In university there are a lot of different groups. For extroverts/introverts gaming nerds. You just have to go and meet them. That pretty much solves the issue.
If you start working right away (and don't have to attend school for that), it'll be way more difficult.
And I think the area close to the border is a pretty rural area. Meeting similar-minded people or finding clubs might be difficult. I always recommend meeting people while doing something you like. Because you'll meet people who have something in common. A hobby or something like that.
Or find a youth center, do some volunteering... Find out where the local computer nerds meet. Maybe a sports club. There are introverts everywhere and the atmosphere of every club is different. Ofentimes you have to try and find out if you're feeling accepted there.