Rearing and bucking 2 yr old! HELP?

I have a 2 yo filly that I am training. She is amazing at the walk but as soon as I ask for a trot, she throws her head down then rears up! And at the lope, she will buck up just a little bit. I ride her with a bosal hackamore and sometimes a snaffle bit. She is the first horse I have ever trained and other than those problems she is really great! She (sometimes) flexes at the poll, backs up like a pro reiner and stops on a dime!