Found Sac but no baby

M

The date my last period started was Oct 16th, which would make me measuring around 10 weeks. Today was my first doctor appointment and they didn’t find a heartbeat or sac, so they sent me to do a stronger sonogram and they found a sac but no fetal pole or baby inside. Has anyone ever had this happen? I wouldn’t think I was that far off with measurements because I had been logging my periods prior to pregnancy.