After a long long flight (actually, flights!), and a few days of jet lag, I'm back at work again! It's hard to get back into my normal routine, though - it's like my brain and body have forgotten what they are supposed to do!
I started working out again yesterday, after taking a break while I was away, and my muscles today are telling me that they weren't prepared for that type of movement yet... All the strength and fitness I gained last year seems to have disappeared! Has this ever happened to you? You feel like you can't use the same weights you used before, or you can't run for as long, or as fast, as you know you can. It's disappointing!
So I have some bad news for you... language skills are a lot like fitness skills. They are great - as long as you keep practising. When you stop, unfortunately you lose some of them. Now you don't go back to zero - you don't need to start from the verb to be again! - but you might find that you can't remember words that you are sure you knew, or that you make more grammar mistakes. Or maybe your pronunciation isn't as clear (I know that my Portuguese pronunciation isn't great right now because I spoke English 98% of the time I was away!). All those things are there, somewhere in your brain. But you may need to work a little harder to get them back so you can use them again.
This is why I can't give a direct answer to 'how long will it take me to learn English?'. It's like asking 'How many years do I have to go to the gym before I can stop and not go anymore?' There's actually no end; just like fitness, it's something you maintain, not something you finish. The good news is that you don't need to study all the time or work harder and harder. You just need some regular practice to keep what you've built. I don't want this to be discouraging - there are lots of (fun!) ways you can practise to maintain your English. But I do want to encourage you to think about how you can maintain the English you have learnt, even if you aren't interested in improving it right at this moment.
How often do you really use your English outside of study time?