If you want to get a lot better at piano, do this immediately:
Think of something you can play easily and learn 20 more pieces at the same level.
It can be 20 pop ballads, jazz tunes, Bach Minuets, or anything else. It doesn't matter.
What matters is that you build a strong foundation for moving forward. Not many piano students do this, because it seems counter-intuitive. But all the pros have done this. Elton John did. Bud Powell did. Mozart did and so did Tori Amos. They became extremely fluent at what they could already do easily.
You can do this too. In fact, you've probably already dismissed this idea as being "too easy." But it's not. It what will help you improve the most.
After all, you don't jump up a mountain. You already know how to put one foot in front of another. So take a step. Then 20 more. And when it starts to get harder, you'll be ready. Just like with the mountain.
Here are some free piano improv lessons. Enjoy!