Measuring behind

Louisa

I went for an ultrasound a couple of days ago, all my apps were telling me I should be 7+2 days but they measure baby as 6+4. It just makes me nervous because I track my ovulation and I was 100% sure when I ovulated. We also only had sex a couple of times around then so it wouldn’t make sense for me to be 6+4. Has anyone else had this? Hopefully I’m just overthinking…