Can you charting/cycle gurus help me with my dates?

[DeChRi]

This is #4 and a surprise, so I was not agonizing over dates. (I was on BCP, so not charting to avoid or anything).  My periods had been irregular due to a pill change, but the date of what I think my last "real" period was, was July 20.  My cycles tend to run a few days longer than "normal" and I tend to ovulate a bit later than "normal" two, based on my limited charting while TTC #3.  We all had been sick, so I 100% sure that our August 6th date night was the magic day.  I noticed some egg white mucus the next day, Aug 7th, which is what first made me nervous.  I got a BFN on Aug 13, no test on the 14th, and BFP on Aug 15th.

I am trying to accurately determine when I was more likely to have actually ovulated.  I know the normal is "sex 2-3 days before ovulation is most likely to result in conception".  So does that mean my likely O date would have been the 8th-ish?  OR because of the egg white mucus, would the 7th have been most likely?  Could I have had egg white mucus the 7th and not ovulated until the 9th?

Or is it impossible to make an educated guess? :) 

[MarineWife]

you can ovulate several days after the last day of fertile cervical fluid. there's no way to pinpoint the day without temps. you can't even really pinpoint by when you got a bfp because that can vary so much. the best you can do is say you most likely Oed sometime from the 6th to the 9th. a 3 day window is the best you could get with temps, too, so don't stress over the exact day.

[DeChRi]

THanks. :)  I figured that was the case.  I'm not really concerned so much as trying to think through my best guess at actual dates, since I will need to figure out what to tell my OB to get my EDD set right.  My only option this time is a hospital birth, and luckily, I have a great relationship with my OB.  She will ask my opinion on EDD as I have proved to her 3x now that I am good at charting my own cycle (until now, lol).  The first two DCs I padded it a bit so I wouldn't go late and have to mess with the induction argument.  However my last one was thinking about making a debut more than 2 weeks early, which they automatically stamp as pre-38 weeks here and that loads them up for a bunch of extra stuff I will have to bicker about.  So I am to hit it as close to the button as I can. :)  I am thinking I will go with either the 7th or 8th as O date and work with that. 

After reading back through, I am most certainly overthinking, lol.

[MarineWife]

a couple of days in either direction shouldn't be a concern to your ob. i'd pick the middle date.