My periods were due on 29 sept but didnt got.. till today so far.. n still have negative urine test... on 29 sept i gone through usg scan abdomen and it came out normal but endometrium thickness was 6.1mm and doctor said ur periods will come approximately 2 weeks later but it came on time 30 sep.. n flow was low.. and this mnth no periods.. 8 days late n negative test.. what does it mean..