Hannah i really hope and pray that all is ok with you i had the same problem at the start of my pregnancy my first scan showed only a sac and the second scan showed sac and baby so my dates where also wrong i thought i was 2 weeks ahead but i was wrong i had bleeding on and off from 5 weeks until 12 weeks and thankfully all is ok with our little one all the scans showed it doing great hopefully this is a little peace of mind for you and im hopeing your baby will be fine and healthy, stay strong and keep us updated