Missed miscarriage???


So 2 weeks ago my boyfriend and I went for my 2nd OB appointment. They did a transvaginal ultrasound to measure the baby to see how far along I really was. I measured 6 weeks 3 days. I could see the tiny little heartbeat. They wanted me to come back in 2 weeks for another to make sure my little peanut was growing properly. I came back Friday (the day before my bday) and they said they didn't see anything and that I lost it right after the first ultrasound. I was absolutely devastated, and couldn't stop crying. This was my first pregnancy. After we got home I was talking to my boyfriend and he brought something to my attention that I didn't even think of at the doctor's office. I haven't started bleeding yet! How long after the loss of a baby do you start bleeding?? Should I get a second opinion?? I have a little cramping but that's about it. Is this normal?