Empty sac @ 7 weeks 1 day U/S

MD

Went in today for my ultrasound.. I’m supposed to be 7 weeks 1 day according to my last period however I ovulated on the December 12/13th (late) ( it took me 40 days to get my period after my D&C in October after having a miscarriage due to pregnant with an IUD) so if I go off that I’d probs be like 4ish weeks i think.. the doctor said that I could still be really early and that could be the reasoning. got blood work taken & go back again for more Thursday to see if my numbers doubled. Has this happened to anyone else?? what was your outcomes!!!?