Hello, I'm 3–4 weeks along. They admitted me to the hospital for a det…

Hello, I'm 3–4 weeks along. They admitted me to the hospital for a detachment; there was brown spotting. I'm taking Duphaston. At the hospital they said the ultrasound machine was poor and they could only see the gestational sac because it's such an early term. I went to a private clinic: they did an ultrasound, saw the embryo and heard a heartbeat, but said the heartbeat is very weak and the embryo is small and may not survive. But should it really be bigger at 3 weeks? Tears streaming....