Hi Im 20 years old, I started my period on 08/04/09 my cycle always runs a pattern of 25 24 23 religously and the last one was a 25 day cycle my possible ovulation days were 08/11/09 - 08/21/09 according to www.americanpregnancyassoiciates.com. This web site has been very reliable with helping me caculate and learn my cycle I get all my possible menstrual dates from there and it always predicts correctly. The thing is I've been having unprotected sex with my boyfriend each day of expected ovulation. I know I may not be pregnant or maybe Iam ! Just wanted some extra voices to give there opinion. My next expected menstrual period is not due till 08/29/09 which will make the mark of a 24 day cycle. Yet I've been feeling funny ever since 08/16/09 like my period is coming I had sore tender nipples that subsided shortly after 3 days but its these irritating twinges and stabs some where inside I guess the lower abdominal area and contractions in the cervix. My uterus linings feels like period time but it felt like that for two intire weeks this is nothing that happens to me regularly if it does happen it happens 2 days before my expected period. How could I forget my lower achey back OMG soooooooo painful at times but never a brake from the lower back :(. All these symptoms are period symtptoms but happening too early.