Wow, you have a truly unique mix of languages in your family! :)

I thought about this a little more, and yes, community did help me develop my mother tongue a lot. There were the parents who exclusively spoke the language, but I would frequently visit my grandparents, who would also speak it. And they would take me to visit other members of the clan, who would also speak that. Perhaps it is a diversity of people speaking the language that gives one a certain amount of fluency?

I learned Hindi because it is the national language and my peers in school usually conversed in it. English was what most books were written in and it was the language of instruction. So it seemed very natural to be fluent in multiple languages.