First, Thanks for your response.

I feel confident with my English. I don't feel bad when I don't know how to say something and I can't talk in almost situation. However, in the IT field (and in almost all professional fields) you have to speak properly to be considered an "expert". I'm not talking about having a different accent, I'm talking more about things like using the proper verbs tenses or the best sentence structure. This is what I want to point out when I refer to fluency.