No heartbeat at 8 weeks

On Friday I had my first ultrasound at 8 weeks 4 days. I didn't know what to expect but I knew something was wrong when they didnt let me see the screen or call my bf in after checking. So after the ultrasound we went back to the room & waited for the doctor, I was nervous & anxious. I've had a miscarriage before it was painful & like a period. I knew they would be a chance that I could have another but i still had hope. The doctor finally came in & told us they couldn't find a heartbeat & the baby was measuring 6 weeks instead of 8 weeks. He said he's 100% sure that I'm miscarrying if my cycle is regular & im certain of my lmp but im not sure if my cycle is regular .I got a second opinion at the emergency room & they said the same thing. However i feel there's a chance of the baby still hanging on because my hcg levels are still high & I'm not having any miscarriage symptoms whatsoever. If anyone has experienced this please help me understand.