Very worried...

Yesterday I went to the doctor for an ultrasound a check up and as usual the doctor had trouble seeing the baby (it's harder because I am plus sized) When he finally found the baby we only got a short glimpse and in that short time he could not confirm a heart beat. The baby is quite a bit bigger than when we looked a little over 2 weeks ago but I am freaking out now... he wants me to go to the hospital for a better ultra sound but they can't get me in until Thursday... so now I have to wait and hope and pray that my little one is ok...