What are my chances ?

So this is my second pregnancy and according to this app I should be 8 weeks but today I went to the er due to a light bleeding, the doctor said that the baby is measuring 6weeks and the  technician couldn’t find a heartbeat... and my hcg levels are on the low side too 1340 I’m gonna follow with my doctor to see if my levels go up... have you been thought something similar and baby was ok? I really need some perspective

Thank you