all my life!

I don't know why but I've always made the effort to talk like a girl.
I could have been when my mother and friends and father ( D: ) told me my voice was changing, and I, being shocked at what was happening to my body, subconsciously started speaking in higher tones.
Either way, I do still have some trouble hitting a high (HIGH) pitch like those Japanese singers, but I've just began attempting it. And by the way, for practicing high notes, Japanese singers are the best people to model your voice after, I suggest Discotheque by Nana Mizuki. Seriously, try singing in those high notes and your voice may feel tired after trying, but gradually it takes longer and longer to tire it out.
Good luck girl