EDD doesn’t line up with LMP

[Workalldayworkallnight]

Hello, I’m back with another thread as I’ve been thinking this morning and I’m confused and I just don’t get it at all if someone could shed some light please!
I had my dating scan last Friday and was told I’m exactly 13 weeks so I would be 14 + 1 today, but the first day of my last period was 27th Nov 2020 and my EED is 3rd Sept 2021 and that means I would have caught on the day of the first day of my last period which isn’t possible at all because we didn’t actively start trying until the 3rd of Dec 2020, so I don’t know what’s going on at all I’m more than confused!
Can anyone shed light on this as I’m a bit worried like does it mean something that my baby is measuring big and so early on too?
Thank you.

You would have ovulated the first or second week of December if your last period was end of December?
Which adds up to the dates?

End of November sorry.
2 weeks of it you weren't technically pregnant

Basically if your period was 27th November, you will have conceived roughly 2 weeks after that.

I’ve been tracking my periods for years on an app just because they were longer so I just tracked them to know when I would be on next but then when we said we would start trying I started tracking the ovulation dates then that were in line with my period because the app told me when I would ovulate too, my cycles are longer so 33 days and I have my period for about 5 to 6 days so my app told me I would ovulate the 15th of dec but we started trying the 3rd, we never had unprotected sex before then ever and I don’t have sex on my period so the sperm couldn’t have met the egg until the 3rd of Dec, so I’m confused how I’m measuring so early if we’re not really pregnant the first 2 weeks wouldn’t baby measure at 12 weeks now instead of 14? I’m just so confused and it doesn’t make sense to me at all 😂 I might be sounding really stupid but I can’t wrap my head around it at all 😩

Pregnancy is dated from the first day of your last period. 27th Nov was exactly 14 weeks and 1 day ago.. So it's bang on?

@Workalldayworkallnight

I’ve been tracking my periods for years on an app just because they were longer so I just tracked them to know when I would be on next but then when we said we would start trying I started tracking the ovulation dates then that were in line with my period because the app told me when I would ovulate too, my cycles are longer so 33 days and I have my period for about 5 to 6 days so my app told me I would ovulate the 15th of dec but we started trying the 3rd, we never had unprotected sex before then ever and I don’t have sex on my period so the sperm couldn’t have met the egg until the 3rd of Dec, so I’m confused how I’m measuring so early if we’re not really pregnant the first 2 weeks wouldn’t baby measure at 12 weeks now instead of 14? I’m just so confused and it doesn’t make sense to me at all 😂 I might be sounding really stupid but I can’t wrap my head around it at all 😩

Ovulation based on periods is not always accurate. It's just an estimate when you look on the app. It's just the way pregnancy works. The first 2 weeks you aren't technically pregnant. It's just the way they date pregnancy. So you 100% will have conceived in December.

This is an estimate for you. Based on your period on 27th November and a 33 day cycle.

Thanks guys, I know I sound stupid, I need to go back to school for some biology lessons haha! So I would have ‘gotten pregnant’ like sperm meets egg then on the 11th of Dec because that’s exactly two weeks after the 27th of Nov which makes way more sense to me, just I’m still confused how baby is measuring 14 weeks if I wasn’t technically pregnant for 2 weeks haha, sorry honestly I’m making myself confused but it all

@Workalldayworkallnight

Thanks guys, I know I sound stupid, I need to go back to school for some biology lessons haha! So I would have ‘gotten pregnant’ like sperm meets egg then on the 11th of Dec because that’s exactly two weeks after the 27th of Nov which makes way more sense to me, just I’m still confused how baby is measuring 14 weeks if I wasn’t technically pregnant for 2 weeks haha, sorry honestly I’m making myself confused but it all

Not 100% on that date because there's no way of telling exactly when you ovulated. And sperm can stay inside for up to 7 days before meeting the egg.

It's just how they measure it. They include those 2 weeks.
You'd be better off doing some research as to why they add the 2 weeks ect.

Yeah thank you for shedding some light! I’m going to be doing that now, I don’t get that part the most I think! Thank you again!

Dates seem to match up? Pregnancy is dated from the first day of your last period, not from when you conceived.

Typically you ovulate and conceive around 2 weeks after the first day of your last period.

Dates match up. The baby isn’t ‘measuring’ 14 weeks, the date given at the scan adds the 2 weeks on too.
So the dates are pretty much spot on.

How many weeks pregnant you are is the date you actually conceived + 2 weeks.

The reason they add the 2 weeks is because it’s based on the age of your egg. Your follicle starts developing on the first day of your period and then once mature releases the egg (approx 14 day’s after first day of period) if you have sex around that 14 day mark you can get pregnant (sperm can live 5 days but egg only for about 12 hours so really on days 9-15 after your period starts) that is all based on somebody who has a period every 28 day’s. If for example you have a period every 32 days you are more likely to ovulate around day 18.
Basically on the day you had sex which resulted in your pregnancy you would technically be 2 weeks pregnant. My LMP was 6th November (well it was actually the 8th but because I ovulated on day 12 let’s say it was the 6th) and I’m 17 & 1. So you’re dates are exactly right

Thanks guys! That definitely makes more sense now, I must have ovulated early as my cycles are 33 days and my app for the last year was marking me down as ovulating around the 14-15th day every time as I always had my periods at the end of the month always so ovulated the middle of the month after so must have ovulated around the 11th day instead! Thank you everyone for the input and that they just add the 2 weeks on instead of me thinking I caught magically during my period 😂