On the 19th of May (5 days after my period ended) me and my SO had sex, and he ejaculated in me. I waited 2 weeks to take the test and it was negative. Waited another week, negative again. Took another one this week and it was still negative. My period is a regular 28-30 day cycle. I always get cramps, sore boobs and all that before I start my period, but none of that happened and I'm officially 8 days late today. Can anybody help me out here..??