No heartbeat :(

Alicia
7 week scan this morning, and the gestational sac and yolk sac were visible, but nothing else, and no heartbeat yet. 
I shouldn't worry. The ultrasound tech said it was just too early, but that I did measure 7 weeks. I will get another ultrasound in 2 weeks. But I can't help it, I was so looking forward to hearing my baby this morning and now I just feel worried that it's not growing. 
Did anyone else not see anything at 7 weeks, go on to see something at 8 or 9 weeks?