I am Teresa and I am 11 weeks into my pregnancy.. I've had sever morning sickness where I was admitted to the hospital for dehydration. I had an ultrasound done at 6 weeks and it looks like two babies but the nurse says its one. The day I found out I was pregnant I had this gutt feeling that it is twins. My stomach is the size I should be at 5 months along ( this is second pregnancy ) how do I know if I'm having twins?