Hey!! Maybe I can help :)
Puberty sucks. It really does. I hate it. I started fourth grade year... Yikes. Not a happy few years after that XD
With the breasts thing, just keep doing what you're doing!! There's not much you can do wrong there :p
Idk how old you are or what your physical lifestyle is like, so I have no idea when you'll get your period. You're most likely at that age where you start carrying pads or tampons in your bag so you're always prepared!! If you do, uh, bleed onto your trousers, just tie a sweatshirt or jacket of yours or a friend's around your waist until you get home. Believe me, it's happened to me, and the jacket will do!
Listen, you really don't have much to worry about. You'll be fine, I promise!! :)
Best of luck!!