I found out at my sonogram today I’m measuring a week behind instead of being 7w 4d, I am 6w 4d. I did see a heartbeat (tech didn’t say rate), but I feel like the yolk sak looks really large. I did track my ovulation for this pregnancy so I was pretty confident on my original due date. I’m nervous this means it could not be a viable pregnancy. I did have an underactive thyroid issue I was diagnosed with a week and a half ago and started that medication for it.