Low hCG?

My blood pregnancy test came back positive but my obgyn sent me to get another blood drawn because my hCG is too low. Now I am downright panicking and stressing. I don't know what to make of it but I tend to be a pessimistic person so my thoughts are stuck on the worst. My af is due tomorrow since I ovulated a week early. I got my at home positive pregnancy test on Sunday. I don't know what to do or think! Please pray for me!