Not sure about weeks of pregnancy

So I went on Saturday to the ER because I thought I had a miscarriage. They did not find a sac or anything on the ultrasound. They did the hCG test and they were 316.08 so they concluded that either was a miscarriage or too soon to see a baby. On Monday I went for another test and my hCG levels were 548.46. So it almost doubled in 48 hours.. I’m thinking how many weeks I’m pregnant since my last period lasted for almost two weeks so I couldn’t predict my ovulation day.

Can you please help me??