Could they be wrong?

I was told on the 27th in the ER I was having a miscarriage. They did bloods and a transvaginal US. They have found the gestational sac on the US the week before. No sac on the 27th. I was bleeding alot and had very large clots that day which is why I went to the ER. I know my hormone levels was around 1000 when I went in I don't know what it was that day they never told me. It's been almost a week and I just took an hpt. It was positive. How long does it take for hormone levels to go back down? Could they have been wrong? Could the heavy amount of blood been messing up the US? I know this is silly and I'm really reaching for some hope that my baby is still there. This would be my second MC in the last 6 months.