Bleeding???

On Monday, I was spotting brown blood and then it turned lighter red and I was changing out panty liners every couple of hours. Thin thin liners. Anyways, I went to the ER and they saw baby, heard a great heartbeat, and said everything is fine for now. The dr said that there is a 50-50 chance that I'll miscarry. It's too early to tell. He said bleeding "can be very normal," and "hearing a heartbeat and seeing the baby is a great sign." Still scary. I was told I was 9 weeks 5 days, but turns out h OB today said I was 6 weeks 3 days! Anyone else experience this and had a healthy baby?