My German learning experience has been exactly the same. It is frustrating to have plateaued at a certain level. In Berlin I found a tandem partner who grew up

My German learning experience has been exactly the same. It is frustrating to have plateaued at a certain level. In Berlin I found a tandem partner who grew up under the DDR and spoke Russian instead of English which is how I practised. Something I also found is that if you start off speaking English with someone, it is nearly impossible to change your relationship into a German one, whereas if you start off speaking German, it seems to reoccur again in the future. It's like your first impression cements which language you're associated with.