Eight years ago when I started teaching English in the U.K., I taught a Korean student who was crying repeatedly because she couldn't understand anything people were saying. She had been studying English for ten years and on arrival to Brighton, found that English was completely alien to her. Anyone who has learned a foreign language has been in her shoes. It took me three months to understand "Que le vaya bien" whilst living in El Salvador. Then you throw in a different dialect and fast speech and understanding is ten times more difficult. As with Sunny, my Korean student, it took her many months to understand the linguistic intricacies of "stick the box on" (put the TV on) and "I could eat a horse" (I'm very hungry).
Sunny had reached a high upper intermediate level in South Korea and was extremely confident with her English. She arrived to find that her language was transactional and didn't really fit with the British English that people spoke on a daily basis. However, she was more than capable of passing all the exams she required....but she just wasn't happy.
This is where the question of fluency arises - a debate on which scholars struggle to find a binding definition. As a learner of Spanish at the age of 37, will I ever know every word in the Spanish dictionary? The ins and outs of the conditional tenses? Will I be able to have an in depth political conversation where I can accurately manoeuvre through an array of opinions and politely state my point of view? More likely, I will be able to (hopefully) one day, be able to speak Spanish without feeling like a fraud. This is my idea of fluency. My personal fluency.
In my mind, fluency is personal to the learner - and all learners are different. Sunny possessed one type of fluency but desperately wanted another. The most important aspect is to understand and discover your idea of fluency which will lead you to being comfortable with your English - be that for passing an exam or living in Manchester for three years. Language belongs to us all and it's up to you to define how far and in which direction your language learning journey will go.