Let me give you a sense of my level in English. I've been in English-speaking schools for many years, and nearly all my interactions with my peers are in English, but I've noticed that I have trouble with everyday expressions, like "turning on" the light (not "opening" the light).
When I speak, I'm often impatient to get my idea across, so I sometimes utter blatant mistakes, like "My needs are little" when it should be "My needs are few." People have said that I have a slight accent.
I consider my written English to be pretty good though. I've been doing it for a long time, and I always get high grades on language/written style on essays.