If my period date was unknown. Then how can I find when did I actually get pregnant.is it ultrasound scan give accurate results for the pregnancy month. Because September and October I missed period ,but September 28 pregnancy shows negative on urine and blood .again October 28 o checked pregnancy test it shows positive and ultrasound show 7 weeks 2 day.and dye on june 13.from ultrasound scan how can I find when did I actually get pregnant