Is it normal for a teenager to spend so much time in their room?

I do go out with my friends too, but I like my own space. My mum doesn't understand and thinks I'm doing it because of her. I get really bad mood swings as well so staying in my room prevents me from taking it out on anyone. Also I have two really annoying little brothers (5 and 2, they run around like hooligans and I'm 14 soo..) anyway, am I a freak?