Could it be possible? Help me!

Ok ladies, today is the 8/9/20. I went for an ultrasound and I am supposed to be 8 weeks pregnant. The scan however said I was 5 weeks and baby has no heartbeat. She suspects I will miscarry soon but she also said you may have ovulated much later then you thought so I should wait two weeks and scan again.

Ok so here it gets complicated.

First day of my last period : 15 July

I have a 30 day cycle.

I tested positive 14 August

Today is 8 Sep

Is it POSSIBLE that I am only 5 weeks? Or based on the dates is it really a miscarriage.