What Causes White Vaginal Discharges Instead Of Periods?

hi,i am 24 years old,my hight 5'2'' ,my weight 45 kg. i had my periods 16 april,2011 &now its 4th june.during this time i have noticed i haven't gotten my period.&these days i got white color from the vaginal area. plzzz...help me...i am too much worried.