I did a post on language fluency a while back, but I wanted to talk about fluency a little more. You might wonder what it takes to achieve fluency. You might also wonder "how many words it takes before you can consider yourself fluent."
I used to think in those sorts of quantitative terms. I thought that if I got to a certain number, and it had to be somehow measurable, I would be at the point where I was fluent.
That's not really the way to think about it. You can have a vocabulary with very few words, but be at the point where you have practiced them very well and can fill gaps of words you don't know through intuition and contextual clues, and then respond without hesitation with the words that you know.
Or, at the other extreme, you could know a very large number of words, but still not have them embedded verbally to the point where you recognize them well and can easily create different forms of words out of them. This is closer to where I am. I probably have about 6000 Polish words that I have learned to the point where I can produce them fairly easily (that's a conservative estimate as I have about 10000 in rotation on Anki plus about another 4000 phrases and sentences), but have a difficult time recognizing them in conversation, and have some difficulty consistently producing them in the correct grammatical context. I've probably gotten more fluent in some other languages with less words learned.
But that is OK for me. I really enjoy learning new words, and so I have focused my learning on vocabulary more than most would. You can tell that my posts mostly focus on vocabulary and the interrelationships between words and parts of words. I'm more interested in "słowotwórstwo." And I'm confident that at some point the fluency will arrive; maybe at a point that is later than it would be for a person who concentrates more on speaking and grammar. But when it does arrive, I think I'll have a high breadth of expression.