first of all, it was really hard to read any of that.
second of all, Itachi isn't a girl, and therefore, there is no 'a' at the end of his name.
third of all (and now I'm getting into your questions), it was Itachi who killed his clan, wasn't it? or did I miss a chapter, somewhere. Itachi killed them all with the help of Madara.
fourth of all, Sasuke was a little kid, who loved his brother. he didn't want to kill him (at that moment). he decided that he would kill Itachi (not Itachia) after Itachi told him to cling to life so he could kill Itachi. and even if Sasuke did use a fireball, don't you think the Uchich would've fought back against Itachi, so what would that have done if Itachi could kill off the best police force Konoha had. I don't think one fireball from little Sasuke could outdo all the retaliation that would've been given by the entire Uchiha clan, excluding Itachi (duh), Sasuke (also duh), and Madara (and everyone who was dead, once again, duh).
wasn't it Itachi who threw the kunai at sasuke, just barely missing his face?