is this how it works?

[x.Lilly.x]

My last period started 22nd july. im not sure how long my cycle is but im guessing we concieved somewhere around 14 days after first day of period. i thought u calculated how far u were from first day of period wich makes me 7 weeks tommorrow but i had a scan today wich only showed the yolk sac and another thing and she made me 5 weeks. if you count how far gone i am from the time i concieved then i should be 5 weeks yeah but i always thought u worked it out from the day of your period? although that makes no sence to me as your baby wouldnt start growing until you concieved would it?
My bran is confused, just need someone to explain it to me in simple terms as im rattling my brain over how im only 5 weeks.
i also got a digi 1-2 (so 3-4) on the 28th July and then a 2-3 (4-5) on the 29th of july. although i think the 29th one may be wrong as if i go by the 1-2 week one i guess the 5 weeks 1 day today is right? xx

 

[Sam's Mum]

Weeks are counted from the first day of your last period, which - if you have an average 28 day cycle - means you conceived 14 days into your last cycle. If you have longer cycles or irregular cycles the LMP date doesn't mean a lot, as ovulation (and conception) is unlikely to have occurred 2 weeks after your LMP. If you weren't charting and don't know exactly when you ovulated I'd take their word for it and go by scan dates, as they are far more accurate x x