"How can I reach level C2 in English?"

If you're already at C1 without much outside help, you've done quite well! However, moving up to C2 means finding someone to guide you.

"Just chatting" doesn't help as much as you'd want, because a lot of errors get ignored in casual chat. The focus tends to be more on being understood than aiming for a native way of expressing yourself. The same goes for workplace situations: if "understandable" is your standard then you're only using the bare minimum.

You do need to set higher standards for yourself as you improve. I know this sounds obvious, but I often meet students who think it's enough just to know more words and more grammar rules.

Have a look at what you write and say, and ask yourself if it's truly correct and natural. You may find you've been carrying errors since elementary level because you weren't aware of them. Again, find a guide who will honestly tell you what's needed and train you to bridge that gap.

If regular teaching sessions are out of your budget, you can still use italki's Notebook section for writing practice (ask lots of questions!), and you can also record yourself, upload the audio and post a link here in Discussions. As a community, we'll be glad to give you feedback. :)

@Irena, waw! That’s interesting and think it’s the proper way to achieve C2 level in any language. A good basis of grammar and an enormous amount of time exposed to that language.

Thank you for sharing your experience, I was always wondering how you reached your high level of English.