I feel this whilst learning (trying to) German: when I think "how I would say this in German?" I got nothing less than a blank on my mind. But I'm a good "speaker" though, and sadly, I feel I'm not going anywhere as well...
Surround yourself in the language. In Germany we have almost everything dubbed, so you can watch pretty much any popular movie or TV series in German or read any popular book in German. Besides that there are also quite a lot of German productions.
Watch Dark on Netflix in original German on repeat, great way to subconsciously make note of tones and pronunciation while also watching an awesome show. Be very intentional about it though.