Today I got an ultrasound at 6 weeks, but it turned out I'm actually 5 weeks. They couldn't see the baby yet. They said there was a yolk sack (sack or sac?) so that was a good sign. Is the yolk sac/k just the black part on the ultrasound? Or is their some kind of lining in the black that is the yolk sac/k? Haha! I'm an idiot! Sorry. Or is the black part the placenta? Whaaaa?