What's my first language?

I was doing a communication subject tute work the other day talking about challenges we find in our interpersonal communication. One of the question was : Is English your first language?

I thought to myself..okay..how many languages can i speak fluently? Not much. English, Mandarin, Cantonese.

So..which of these 3 is my first language?

Obviously the one I speak at home- English. But i thought to myself...Eventhough English is so called my "first" language...I have never really mastered this language...I speak this language everyday, write this language everyday, listen to this language everyday, but somehow I can just never get good in English. Often there are times where I'd have to google or get on www.dictionary.com when i talk to guns like Devin and Tim on msn. They just like using what i call "big words" (eg sinister instead of bad) thinking that I would understand it..but..i just dont.

So is English really my frist language? Yes but No. Is Chinese/Cantonese my first language? Definitely not in a million years. So what's English then? I tend to call it "My half first language.." which basically means English is my first language but I'm just not very good at it.

I think most Malaysians can identify with me in this way. We know our grammar, it's just that we never use it. We speak English everyday, just not in the right way.

Eh what you doing tmr ah? - What are you doing tomorrow?
you ah, why you always like that one? Why are you always acting like that?
Eh this one how ah? - How do you do this?
Aiyo i dont want la you eat la- No, I do not want to eat. How about you eat it instead?
eh switch off the light- Pls turn the lights off.
aiya i fetch you home la you take bus so mah fan- Don't bother taking a bus, it's too inconvenient. I will give you a lift home.
eh you don't play play with me ah, i know wing chun wan! - Don't mess around with me. I know Wing Chun.

and so on...

I wonder when can I finally call English, my frist language.