[antegamisou]

Since you aren't a native speaker, I believe some degree of imperfection in speech and writing is acceptable especially if the people you're working with are aware of this.

That is not to say you should remain stagnant and not try to improve though.

Many have suggested you take up some form of writing to improve but IME reading high-quality text (newspaper articles, classic literature books) is a more efficient way that will help you imitate the caliber of native speakers in the long term.