When should I start wearing a bra? Now or Later?

I am 12 years old. I have breast buds and not breast, well not really anyway. I also get made fun of sometimes because I dont have breast, I get called flat chested. So anyway my niples show through most or my shirts and i have tried traning bras and they dont really work, but tank tops do most of the time. I also am kinda wondering if i am going through puberty but I am not sure. I have pubic hair and a few zits once in a while. Kinda clueless here. PLEASE HELP!