I'm 18 weeks and I have had 2 ultrasounds ready (the last one was at 13 weeks) and all found one baby. Last night I was listening with my home doppler and I think I heard 2 separate heartbeats... I know I found my own, but I also found 2 faster ones...one was 145, the other more like 135, and at one point I heard the 2 fast ones overlapping at the same time. I am in no way an expert- this is my first baby- but I'm just wondering what are the chances that they missed a twin??