Is there something wrong with me?

I'm 11, and just starting puberty, So I know that when you go through puberty your supposed to go through a lot of mood swings. So earlier today I had a mood swing and I got really annoyed and angry at my friend who is only 8, and I pushed her. So like 5 min. later I went to a corner and started crying, so when I was crying, she was walking towards me and I told her to go away.Then later I told her I was sorry, but these questions was still in my head: Am I turning into a monster? Is it okay for mood swings to have such influence on your words and actions? Why can't I control what I say so easily any more?