Please don't judge me

I recently found out im pregnant on the 23rd went to the hospital because I was having lower stomach pain they took a pregnancy test also blood said I was pregnant.. then they took a ultrasound didn't see a fetal they told me I can be to early in to come back or go to my obgyn within 2 to 4 days MY QUESTION IS IF I HAD intercourse WITH SOMEONE ON SEPTEMBER 11TH. CAN I BE PREGNANT ALREADY? I DONT REMEMBER WHEN I HAD MY PERIOD LAST MONTH 🤦‍♀️ OMG THERE IS SO MUCH TO THIS STORY CAN SOMEBODY HELP ME