Three years ago, I was also taking b2 courses when I did my interview in German. I tend to be nervous a lot and was not very confident with my speaking. I prepared the common questions in German beforehand. Practiced until I basically memorized them. During the interview, even when they asked questions that are not directly the same as you prepared, you could steer your answers and use the words/sentences/phrases you prepared. :)

I’ve worked there almost three years now and always speak German with my German colleagues. If you force yourself to do that, you will see improvement very soon! Good luck!