I think my answer won't be so useful because we have had excelent
answers for your question.
What I can say about your question is that it has happened to me at a moment where I thought my E
nglish was good.
Here is my history: I accessed those chats where people use them to talk to each other to practice E
nglish and I came across with an Austrian guy and began talking to him by webcan on Skype.
So he tried to explain me where Austria is (located) and that moment make me to realize that his vocabulary was better than mine so that he talked "border" and I didn't undestand what he was talking about. Border means "fronteira" in Portuguese.
After talking to my Austrian's friend, I got so frustrated with my English level and decided that I would do anything to increase my vocabulary.
Today I have the habit of writting down any word that I come across and I don't know its meaning, and I always come back to review them later. Thus day by day I've been putting those words into my English vocabulary.
Nowadays I don't worry about speaking English in the right way anymore, because now I can get more fluency into conversation even when speaking, of course making a lot of mistakes.
Of late, I don't bother where my English level is because I focus on increasing my English vocabulary and little by little use those words into my conversations. Escrevi em inglês a minha resposta para você ver que nem sou tão bom assim e não importo em escrever errado. O que importa é comunicar e aos poucos corrigir os erros. Se não sei me expressar de uma maneira que me expressaria em português, e não sei dizer em inglês, simplesmente uso outras palavras afim de conseguir me comunicar.
Yesss, this is the right attitude towards learning, I bet you are so confident that no one would notice or would let some minor mistake pass. I got it corrected just because I am such an stickler for grammar in writing, ha ha
Just kidding around. I left your last part as an incentive to us, a good reminder. And Lucas, your method is working, you can express yourself very well.