Poofy hair help?? out of control?

i had long hair and i got tired of it so i (literally!) got it chopped off. now it falls to right above my shoulders and all it does is poof out. i've tried straightening it but it just poofs out again. i dont do a whole lot with my hair, usually just a ponytail, but its getting kind of boring. i want to be able to wear my hair down but i dont want it poofing! what do i do?