Is it normal to be a different person a lot?

I don't understand who i am. I always make myself a character sort of.. It's different proabably every 2 or 3 weeks. I've been this way ever since i was in 6th grade probably and now im 18. I take after famous people or even just people i know personally. I have this pretend life, pretty much playing pretend like im 6. is this normal?