ok.. we went through this with my nephew.
it really takes a lot of nerves to do this but it works wonders quickly.
TOTALLY IGNORE THE BEHAVIOR
.. she hits: dont say a word to her, just take her away from who she hit and move her on to something else.
.. she throws things: leave them on the floor and act like it doesnt even bother you that its done.
.. she throws a fit : lay down on the floor and just lay there. she will be so shocked that she wont know what to do.
whatever you do.. DO NOT YELL at her
now.. on the other side of this you got to really reward good behavior.and make sure to really reasure her that you love her, that youre always there, that you wont ever leave.. and that shes a good girl.
try making a small reward chart. if shes good that day, give her a star on the chart, if shes bad.. she doesnt get one.
when she gets so many, she gets something nice.
like an hour of uninterupted play with a parent;}
she may yet be too small for the chart thing, but it works;}
stay strong.. this phase does pass..
i grew up with a kid that was the worst behaved meanest brat youve ever seen... and hes in his last year of med school and the nicest man in the world. so.. she will grow out of it.. you just might need a wig before its all over.. lol
good luck and keep your chin up ^^