Please help im so sad

DD has started biting. I dont know why, she hasnt met any other kids that bite, or and rough kids, shes just started all of a sudden and i hate it!

Shes very tempermental, has mega tantys if she doesnt get her own way, shes very independant. but i jsut put that down to age? and that all babes are different

But the biting is really getting me down I have a friend who has 5 kids, (2 not hers). DD plays great with her two 8yr old boys, and her 3 yr old girl. shes got a 9 months old lil girl too, Grace, who is the most lovable gentle giant (shes a big girl!) the complete oppisit of DD. my DD is so rough with the poor bub, G isnt moving yet, she just sits, shes trying to crawl and she really wants to play with DD but freya just gets psyco at her and tries to bite her it makes me so sad, i wanted them to freinds

And then today i had another friend over, her bub is 14months, she and Freya played pretty well together, but then she had something Freya wanted and Freya tried to bite her. Bella just turned around and pushed her over but still, i hate the fact that my child is acting like this She hasnt tried to bite me, but her tantys and her attitude lately are driving me nuts! its really getting me down

What do i do about this behaviour???? please help! Ta