No Heartbeat at Six Weeks

I went to the OB today because I woke up bleeding and few blood cloths. I'm not supposed to go until next Thursday when I'm seven weeks and one day, but so much blood scared me that I thought I was having another MC. They saw me right away, and said that everything looked fine, but things are too early to tell. The OB even tried to look for a heart beat, and could not find anything. Is it still too early to find a heartbeat in six weeks and a day? I read that you could.