I had sex dec 27-jan1, had a one night stand on the 5th and took a plan b pill. lmp dec9 due date sept27 vomiting jan 10. maybe pregnancy signs what re all posible conception dates? was i preg alredy

Jan 4: Your LMP and due date don't coincide, so I assume your dates were changed by an ultrasound. That means conception occurred Jan 4. However, if the ultrasound was in the first trimester, it is accurate within 4-5 days. Therefore, the conception date could be 4-4 days before or after. If you are concerned about paternity, you will need to have the baby tested after birth.