5 weeks and no fetal pole

Okay so a little confused here. I went to the doctor today because I have had some spotting and they asked me to come in again, well LMP was Feb 12 so I should be 6 weeks (I know I could have ovulated late) but they told me that my endometrium is as thick as it needs to be for an early pregnancy and there was a sac but they could not see a fetal pole and my urine analysis come back negative. I took a blood but of course it’s going to be 2 days before the results will be in. Has anyone else had this problem??