if you are 6 weeks from the first day of your last period then you would have conceived which they figure in the due date and give you a 2 week period in which you would have conceived so over all gestational sac should be around 4 weeks inter-uterine. So I am 28 almost 29 weeks along I never had a period so I am exactly 28 weeks along. I conceived the day I finished a miscarriage. But other woman would be 28 weeks pregnant babys gestation age would be around 26. Did they do a beta hcg?
I would go get checked. Cramping isn't a very good sign and neither is the blood stain discharge