Trying for a baby, succeeded, now need to know LMP
Okay so I had my period dec 5 had sex dec 9 took after day pill the next day had unprotected sex again for about three days straight but got my period dec 17 for a week guess the pill gave me a second period that same month after that period I started trying for a baby took a pregnancy test on January 10 & came out negative on January 28 took another pregnancy test and came out positive and yes I'm pregnant now my wich would be my lmp ? My due date is on oct 3 at first they went by my lmp that would be 8 weeks or so when I had a ultrasound my obgyn change my due date to oct 3 so which lmp should I use or what happened ?