I am 13 weeks pregnant. I have had one ultrasound at 6 weeks. The heartbeat was barely audible at that point. The doctor indicated that he only saw one baby. However, I was convinced that I was having twins. I know it is possible for one twin to hide behind the other one on an ultrasound, especially that early. Am I crazy for still thinking that I may be having twins? I am showing a lot of signs of a twin pregnancy. I have had several dreams about twins and other people have made comments too. What are everyone's thoughts? Has anyone else experienced this?