Pls anyone help me

Now am 38 week pregnant but my week are based on ultrasound because I don't know my last period date. September and October I missed period but sep28 I checked pregnancy it show negative on urine and blood test on hospital again October I missed period and oct 28 pregnancy show positive and 7 week 2 day on ultrasound. In my first ultrasound my crl is 11.5mn.from this result pls any one help me to find when did I actually get pregnant .

Am upload my first and last scan report from this pls help me anyone to find when did I actually get pregnant.