I live in France and get by pretty well. I sort of still speak English but use French words. That is to say, my structure and stuff I talk about is 'English'. I'm understood no problems but flag myself very quickly as a non-native speaker, even though my accent is pretty good. You learn how to 'get by' and then realise the language is spoken differently. You learn French from whatever source (formal lessons, on-line, tapes, apps, whatever) and then you have to learn over how to use it. I'm of the opinion that to really learn a language (that is, how it's actually used) you have to do it by immersion in the country. I accept now that I'll never be native-speaker level but I can hope for some kind of fluency.
I'm even of the opinion that you can say things in another language that you just can't, or wouldn't, say in English. Many a times I've heard something in French, heard every single word and know what the words mean individually... but put together as they have been, I'm left clueless! How the f*** it means what it means is beyond me. And sometimes I hear stuff and I'll think you just wouldn't even say it English.
And, of course, there are accents and regional/dialects to contend with. Does your brain in at times.