That's the great thing, you never get rid of imposter syndrome! The thing that helped me was the mantra "there's always someone better than you". It's true for everything, so I can focus on just having fun and delegating to those that know more (which is also an important skill since nobody knows everything).

As for improving skills, practice makes perfect. 6 weeks is pretty much nothing. If you work out on one muscle group for 6 weeks, the chances of you seeing significant gains is minimal. You've gotta stick with it for months or years. Just look at the weight-loss journeys of people - it takes some years to lose their weight.

Don't be hard on yourself, find interesting tasks or sites with challenges you consider interesting and try to solve them. https://exercism.org/ is OK, but there are many different ones out there. I can definitely recommend watching videos that explain data structures visually. They'll make much more sense.

Good luck!