> Also, I learned that the french in school is nothing like the french they speak in France. Sure, you get by and they'll understand you, but french relies heavy on vernacular, sayings and expressions.

Virtually everyone who learns a language in school as you described will feel this way when they encounter native speakers in the target language's country(s) of origin.

The reality of school teaching is that it enforces prescriptive snapshots of the language. It teaches the grammatical "rules" of a language at a moment in time, but these rules are always changing. Common English has changed a lot since 1800; consider how different an English class in 1800s might be from one now, though they are both valid in being called English classes. The classes continue exist, but they are often lingering behind the real deal.

Language is developed naturally by our minds, and its inner workings are still largely unknown to us. The best way to learn it is by actual exposure to it, as it is meant to be used. You are always going to be removed from this reality if you are sitting in a classroom with minimal direct exposure.