Who is more likely to be the father?

[Lg1195]

Okay so the amount of stress i have been through since the 5th of september (the day i found out i was pregnant) has been immense so please dont judge me i already feel like the worst person in the world. Ive been with my boyfriend since august 2014, we've had our issues but he is the love of my life however he broke up with me in june this year after a few months of constant fighting a month later on july 15th i went out for dinner and drinks with a close friend and we ended up sleeping together unprotected but he did pull out and i also got the morning after pill. My ex boyfriend found out a few days later i had been out with someone else and begged me to get back with him and i said okay. I then had my period on the 1st of august which was exactly when it was supposed to be due it was also extremely painful which i assume was because of the pill. I should also mention boyfriend and i started sleeping together again around the 25th of july. I missed my period august 30th and took a pregnancy test on the 5th of september to a positive result. First ultrasound was done on 24th of september and i was dated at 7 weeks 6 days. Second ultrasound done on 29th october and i was 12 weeks 6 days but was measuring 13 weeks 5 days and most recent 20 week scan on 7th december measured me at 19 weeks 6 days so i am now 21 weeks so this puts conception at 5th of august so im extremely confused as i dont think i could have been ovulating then unless the map messed up my cycle or something?! :( unless the scan is wrong and i concieved before or after that? Was my last period actually implantation bleeding on the 1st of august? I told the woman at the first u/s i didnt think it was a real period and she said i think it was because baby is only the size of a kidney bean right now. please help me, im slowly losing my sanity and i dont socialise with my friends anymore due to the stress and guilt i feel from this.

[Lg1195]

Sorry that should say missed period 31st of august not 30th

[AnnieBrooke]

The embryo starts on the day it starts, not on the day it implants.  The measurements you get from an ultrasound are of how big the embryo is, not when it implanted.

[AnnieBrooke]

In other words, I think it sounds like you conceived around August 14.  Don't stress.  Don't stress.  Don't stress.   :)

[Lg1195]

Thanks so much for your response! The only reason i started to think it was implantation bleeding was because i read it can take a couple days to concieve then another 7-12 days for the egg to actually implant which would surely make a difference to how far along you are? :( so i was thinking maybe thats why baby is measuring bigger .... its mentally exhausting thinking about it

[AnnieBrooke]

Though embryos all begin as one cell, and for a little while they divide at a known rate, some embryos grow more rapidly than average and some more slowly.  Because of this, by the 20th week, an ultrasound will have a margin for error of a week and a half, if someone were to try to use it to determine a conception date.  By full term, it could be as much as three weeks off.  You had a seventh-week ultrasound, that will be the closest to accurate.  Don't try to spin theories about implantation bleeding or any other stupid stuff, count on the info from your first ultrasound if you are going to try to do this kind of count.  (I should also point out, even if conception happened on August 4th, which it doesn't sound like it did, it would not implicate the guy you had sex with on July 15.)  Don't do this to yourself, you dodged the bullet and you don't need to obsess.