Not surprising; it's far more practical to get information across by switching to a language you both speak fluently. If you ask the other person to help you practice the language, it would change the task from "information" to "training", and you'd probably have better luck in speaking German if that's the expressed goal.
Communicate your wants, or you'll end up with the most efficient route to the end of the interaction. 'Tis the German way.
That sounds horrible. I struggle with energy a lot, but not to the degree you're describing so I can't imagine...
I generally think we should be careful with self-medicating, and I don't know if this is allowed on this forum so I'll accept any consequences:
Have you tried amphetamines/stimulants? Like a very low dose, not anything to make life a party but just a hint to get yourself going, lower than anything you think of. Only early in the morning and no refills during the day, so it won't interfere with your sleep and won't build tolerance. And only pure shit, a thoroughly tested substance, not street-meth or other untested garbage that can be mixed with fentanyl and cocaine and a host of other substances - I mean like actual adhd-medication.
It's not going to solve whatever underlying issue you have (unless it's ADHD, lol), but if it makes you function and feel better it while figuring it out it could be worth it. Ideally as prescribed by a doctor to monitor your heart and health over time.
Regardless , I hope you find whatever you need to feel better and more energetic.
Are you sure you're underperforming, or is that just an idea you came up with yourself? Have you talked to a boss or manager about their expectations for your role and if you are meeting those expectations?
It may just be a self-sabotaging thought, and getting confirmation that you are meeting expectations could let you relax and work at a preferred or natural pace without stressing about your performance.