hi.....my periods were due on 5th july, 2012 but i have not got them yet...me and my husband had unprotected sex around 17th june,2012, but he did not ejaculate inside me because we do not plan a child for now...also, i do yoga in the evenings about 4 times a week...around 3rd of july, i could feel that im about to get my periods but did not get it for the next two days....i have been doing inversion exercises for my back, which i found out is not recommended as it may delay periods...however, it has been over a week and i have not got my periods yet...yesterday, that is on 12th july, i did a self pregnancy test using the pregnancy test kit, and it came negative...im quite unsure then why have i not got my periods....can u please suggest what should i do as we do not want to have a baby now? please suggest