They say that dreaming in another language is a sign you're fluent. I don't think that's necessarily true. When I was taking my A Levels I often had dreams in Spanish but that was just a combination of recycled pieces of vocabulary I'd studied just before going to bed and stress about the exam. But four years of Spanish at uni, one Spanish boyfriend and 18 months living here and I'd consider myself fluent. And the only dream I have in Spanish is one about me failing my oral exam.
There are varying definitions of fluent- some people measure fluency in number of words and grammar structures you know, others use a more qualitative method; can you get by? Can you ask for directions and write a formal letter? For me, fluency is not what you can or can't do in a language, it's about your attitude towards it.
Here's my list of signs you're fluent in a foreign language;
1) You stop looking for opportunities to 'practice'.
For me this is the most important sign of being fluent; that you just don't care what language you're speaking. You can have the same conversation in both languages and you don't feel the NEED to practice your Mongolian any more. You avoid 'language exchange meetings' like the plague.
2) You can have a meaningful relationship with someone who doesn't speak your mother tongue
You can talk to that person without the safety blanket of your first language to fall back on. You also stop looking for foreign friends just because they're foreign. The fact you have different native languages is insignificant.
3) Going to the hairdresser doesn't scare you
You're so confident in your language skills that you'll bet your hair on it.
4) You know when google translate is wrong
Which is a lot. Which is why you never, ever use it.
You can watch stand up comedy in a foreign language and not have to pretend to get the jokes. And if you don't get something, you're not ashamed to ask why its funny; because its probably some cultural reference you're not familiar with, you just didn't catch it, or it simply wasn't funny.
6) You can do boring, adulty things in that language
Like open a bank account, have a job interview or do your tax return.
7) You're not flattered when people say you speak well
You speak well because you were either brought up that way or because you worked damn hard at it. You don't need a compliment from a stranger to make you feel good about your language skills. For me, I just feel patronised when people tell me my Spanish is good. I know they're only being nice, but it's kinda like telling a doctor that his knowledge of medicine is good. You bloody well hope so when you've paid for a degree in it. When you actually speak a language well you don't need people to tell you you do.
8) People don't automatically know where you're from
It's not that you're mistaken for a native speaker, but the occasional tilt of the head and "you're not from here, are you?" or "what is that accent you have?" means you're a lot more fluent than someone telling you "your German is really good (for a foreigner)". When someone can't tell where you're from; that's a proud moment.
9) You're tired of 'oral' exam jokes
It was funny to begin with, but you're over it. Now when you hear the word oral you don't think of sexy time, you think about sitting in an uncomfortably small room with a stranger and having an awkward conversation about something you know and care little about.
10) People don't change the way they speak when they talk to you
They don't slow down or simplify their vocabulary to speak to you. And if they do, you notice, get annoyed and tell them that you're not an idiot and you understand perfectly well thank you very much.
11) You sometimes don't realise what language you're speaking (or reading)
It's a real downside to being fluent because people think you're being pretentious, or you're showing off. You're not. It's just your brain is so used to switching between the two languages that sometimes it forgets to flip the switch back. And sometimes it processes information without noticing what language it's in; like not noticing when a text changes font (like this).
12) You've had this conversation before;
"What does x mean in Spanish?"
"I don't know, it depends on the context"
"You don't know? How do you not know. I thought you spoke Spanish"
"Then how do you not know what x means?"
Unless it's something like 'apple' or 'yellow' most single words are difficult to translate without a context. Only when you're multi-lingual do you get how difficult translating is and how infuriating it is when people doubt your ability to speak a language based on one word.