Real worried

Hey guys so I would be about 8w4d from my last period. I went in for an ultrasound today and they said there was no heartbeat and it measured at 6w3d. They sent me home and gave me the miscarriage talk and how to just let it pass and gave me a check up appt. in 2 weeks. They just called me back and said because of the measurements I may still have a viable pregnancy and they just can't hear a heartbeat because of how early it is.... so they kept my scheduled appt. two weeks from now and I don't understand why they wouldn't take a blood test and make me wait so long after saying I'm going to miscarry it.... can't my hormones tell them where I'm at and where my pregnancy is? I may go somewhere for a second opinion but I'm wondering if anyone had a similar experience or if this could be normal.