Ultrasound

I had my first ultrasound on Thursday, the tech did an abdominal one and said "maybe your not as far along as we think " then did a vaginal one and said she had some concerns about the pregnancy. She had me go talk to the dr, he said to come back in 2 weeks for a repeat ultrasound. They didn't detect a heartbeat, and said I could miscarry between now and then. Or it could turn out to be a healthy pregnancy. Didnt do anything else. Has anyone experienced this or similar? I'm remaining hopeful.