9 weeks bleeding and no baby but gestation sac

9 weeks today and woke up with spotting so I went in and they saw a gestation sac and yolk with no baby. They made it sound like it's possible for me to just be way behind on what I thought I was based on lmp. But I know I ovulated 14 cd. After I left I started cramping and bleeding heavier. How painful was it passing baby on your own. They want me to come in if I bleed heavy but I don't want another d&c because my last one was hell. How long did it take you to pass everything on your own?