Puberty...HELP!!

So my daughter is almost 9 years old. I believe she's starting to go through puberty. She's starting to smell under her arms & has peach fuzz in all the places pubic hair will grow. I've given her the "you're turning into a young lady & here's how deodorant works" talk. I noticed about 6 months ago that she was starting to grow boobs. Now it seems that only one boob is growing & the other is not. Is this a normal thing or should I begin to worry that my child isn't developing properly?