Am I considered immature?

I'm not sure what ANY of that first paragraph has to do with maturity. It sounds like your head was screwed on right and you've got great things ahead of you. You may be in accelerated cles and perhaps ahead of everyone you know, but you're still 15, and at 15 you are still part child. There's nothing wrong with having a good relationship with your father. I say be how you feel comfortable, because honestly it sounds like you have got things under control. It took me till I was 40 to get things under control, you're definitely way ahead of the game.