Living in an English-speaking Country. PLEASE HELP

Hey everyone,
I'm doing a double degree (Law & Finance) in Australia. I'm graduating in 2016 (If everything goes right)
I want to speak English smoothly and fluently (without hesitating and feeling stressed when I speak) before I graduate
I'm not an English native speaker but I'm passionate about language especially in English.

I guess I'm at intermediate level in terms of speaking. I know the correct pronunciation for most words and the correct intonation. But I just can't speak fast and smooth like natives. (maybe I need some practice for my tongue and muscles of the mouth?)

Main question:
I just want to ask if it's possible for me to speak and sound at a native or near-native level in 3-5 years before I graduate?

Am I supposed to immerse myself in an English environment? I do immerse myself by avoiding meeting friends who speak my mother language, go the local church, read books and listen to English music every day. But I don't get many chances to speak with native speakers 'cause it's quite hard to get into their social groups given the fact that I don't speak as good as they do. (But I do get friends at church where I am the only non-native speaker)

Is it extremely difficult for a normal person, who started learning a language in their adulthood, to speak and use the language well and nicely? 'cause I'd like to practice law and becoming a lawyer in Australia

Thank you