You need practice with native speakers, ideally in a setting where you are completely immersed in the language (i.e. hearing it all the time!). I really don't think one can be fluent in the language until they put themselves in a situation where they hear, speak, and read that language 50-75% of the time.

Well, as you say and as I see, you need an experience with native speakers, somewhere. That will bring you the confidence.

more efforts -- less time

I believe half year- 6 months normally.

Can you give us a better idea of what fluent is to you? I mispronounce, mishear, pause, and hesitate hundreds of times each day -- English is my first language. Perhaps you are already fluent but you just doubt yourself?