If I had my time again, I would do the science of language. "Fluent" imo is when a word or group of words comes to the notice of your brain and somehow alters your state of mind with understanding. I've been having a go at learning German for a few years (doulingo streak 2000+) and there are very few words that instantly convey meaning in the way of their English equivalent. Most words are translated first.
One facet of German is that quite often you have to hear or read a complete sentence/phrase before you can understand it, eg "That is the man, who the golf match won". In English we often understand (or think we do) a sentence before it finishes, leading to interruptions and faster paced discussions. Does that all affect the way people think and behave?
FFS! That's in English and I'm struggling with it.