help please!

I went to the doctor wednesday because they said I would be 9 weeks and planned to do my first ultrasound. However, my doctor did not put in my order for the tech to do my ultrasound. So he ended up just bringing a machine into the room and did it himself. He could see a gestational sac, but it was only measuring at around 7 weeks. So he decided to take my hcg and then did it again friday. He called Friday and said that my levels had dropped by 600 (I think this was the number, I was pretty emotional so I may have misheard). He told me to prepare for a miscarriage and to come in next week for more blood work. He said he was 99% sure I was getting ready to miscarry. I have been so upset for the last two days. But I have no cramps, no bleeding, nothing. Is it possible he was wrong? They never even checked for a heartbeat....