US at 6 weeks

After having pink to brown spotting for a week, yesterday it turned to dark red. It didn't last long but my OB had me come in to do an US. Yesterday I was 6 weeks and 2 days. There was a gestational sac and she said what looked to be a yolk sac. She said she couldnt for sure identify the baby or a heart beat. She said this could be normal but scheduled a follow up US for next week. Anyone else have the same finds at 6 weeks and have a successful pregnancy? It's hard not to think the worst when so many other people are posting pictures of their 6 week US with heartbeats..