My period came 3 days earlier than i expected. is it normal? im 16 btw.?

Posted: 07 Jan 2014 01:36 AM PST

i had my period last november 11. then december 11. so i expected my period to come this january 9 or 10 or 11. but i bled yesterday (january 6). is that normal? as for my habits. eating habits is the only thing that has changed. i started to go on a diet. no excercise. just a cut down on foods. and i have been very stressed emotionally. and very scared too before that period. please help?