Ultrasound and scared

I went for my first ultrasound yesterday. I had a miscarriage back in January so they wanted to get me in early. The doc thought I was 7weeks n some days, but that's off a 28 day cycle and mine are every 37-38 days. When I found out hcg was 28 but doubled. My ultrasound showed everything but heartbeat but tech said it was very early around 5 weeks n some days and to come back in 10 days. Worried bc this is the same stage I lost last baby. Any succes stories?