Help, concerned!

Tee
Hi!  I went to doc yesterday and I should be 6weeks 4 days based of lmp, but gestational age says 5 weeks 3 days. Did see the heartbeat yet, but they think it may be too early. I went due to low bp (93/51) consistently around those numbers and dizziness. I did t gave this with my first or second pregnancy. Miscarried before my daughter and I have a 3 yr old. Wanted to make sure this wasn't an ectopic pregnancy. They say everything looks good, so far. My hcg was 3508. Thoughts? Has this happened to anyone?