I need to know if 7week ultrasounds can be off. I don't have a regular cycle and my doctor said it was accurate but I'm hearing It can be two weeks off meaning I wouldn't have conceived until two weeks later... Ive heard a couple days but two weeks?. confused

Give or take a week is very common, and two weeks off is possible.

They are merely using average estimates of development, Also they are looking at last period dates and other factors.

There is no way to narrow it down more exactly. Normally a exact day does not really matter anyway