I have a 2 Week Period? Help!!!?

I am 13, and i got my period 6 months ago. my periods have almost been normal, about 3 weeks until my next period. but this time my period came a little later, and its lasting for 2 weeks!!! It was heavy the whole first week, then like 3 days of light...now its heavy again!!! i don't feel comfy asking a doctor or my parents...please Help ME!!! IS this normal? whats happening to me?