hi, I am 22 years old. My blood group is B negative. My problem is that my last period date was 1st aug. I was with my partner on dated 11th sept, Before it and after it we were not together. That was my first time, I thought that due to pregnancy, my period has not come, si i have taken some birth control pills without any pregnanct test. but it was worthless. then i consult a doctor. she has done pregnanacy test , but it was negative, but she didnt tell me waht is the exactly reason of not coming of perioda. After it, before one week ago, i myself done a pregnanacy test but it was also negative.The name of tablet that i have used, is herwant kit. Can u please tell me waht is reason that periods is not coming while i am not pregnent. what is the reasons for it. Please help. Thanks a Million.