Need help

Helen • Happy family with 8 year old 6 year old and 4 year old 🙂
Hi ladies I'm in need of some advice as I'm very confused. I was thinking I'm 8 weeks 5 days today and I've had my first scan and it's come back measuring 3.4mm and it says I'm 5 weeks instead but my last period was the 7th of April and my periods are 42 days apart. Is this normal