Should I be worried ?

Question

So i got my BFP last Monday and omg im excited. I was late for 2 weeks, ive had irregular periods so i thought it was just coming later. 
Based on my LMP i should be 8w6d. So i scheduled an appointment in a week with my OBGYN. 
I was so curious to know exactly how many weeks I was so I scheduled an appointment with a ultrasound place. 
Tech measured my baby at 5weeks.. so i automatically freaked out. 
My question is ,is this a common thing? Did i ovulate late due to my irregular periods? 3 weeks is a difference. I havent had no bleeding. 
Please help me im going crazy just thinking my baby stopped growing...
Thank you

Answer

Usually when they calculate your due date it's based on the first day of your last period. Obviously if you had your period your not pregnant. It's hard to calculate when you actually conceived so usually there is about a two week difference. So when your eight week pregnant, baby is about six weeks developed. It makes it harder to guess how far along you are with having irregular periods. Sounds like everything is going smooth. Take a breath, relax and enjoy growing your baby

Answer

Scan date is most accurate, LMP isn't reliable for irregular/non-28-day cycles. Not time to freak out yet, and there would be nothing you could do at this early stage if a freak-out-worthy event did happen.

Should I be worried ?

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