I don't think there's a level you "should" be in.
After 3 years of learning, I was not playing very advanced music at all, I think probably pieces like Beethoven's sonatina in F major. (I'm not sure where you're from but its around grade 4 RCM... your Chopin prelude is grade 7 RCM). Coordination wasn't (and still isn't) one of my strengths, I refused to practice, and I was around 11 years old. I didn't have your motivation at all!
Some people might be able to learn a piece in a few days, while it takes others many months.
I know kids who got to level 10 RCM in a year or two of playing piano... it's taken me 7 or 8 !
Everyone is different... we all have different strengths and weaknesses... you kind of have to just work at your own pace

Also, it's not just how difficult your pieces are, or what level you're in, but how well you play.
A good teacher definitely does help in
so so many ways. Such as pointing out mistakes you never noticed before, teaching you how to practise effectively... I don't know what I'd do without a piano teacher!!
Good luck =))