Date of Conception and Accuracy of Ultrasound

[purplewf22]

I found out I was pregnant July 19th after taking a clear blue weeks estimator test which stated I was 3+ weeks pregnant. I had made a comment the week before (around July 11 or 12) to a friend of mine that I thought I was pregnant, I was sick, my boobs hurt, I was EXHAUSTED.
I will back up now. I was on the 3 month pills and not expecting my period until July 17 after having one at the end of April. June 9 (ish) I had what I thought was breakthrough bleeding that lasted a couple days (I know because I got brave and wore white shorts to a party on the 10th). My SO (significant other) and I had sex several times in the month of June but then I made and had sex with someone else on June 30th. I lost my job a week before my first apt and was finally able to get in for a US on September 15th. I was told that day that I was 14 weeks on the dot. Estimated date of conception: June 23rd... EDD: March 16th. 4 weeks later I went for my anatomy screening (we found out we were having a boy at 14 weeks) where I measured 18w4d with the same date of conception and the same given due date. I am doing the paternity test because it will be step forward for us if it comes back his. Thoughts or opinions before I drive myself into an early labor?
I am 33 weeks and 4 days and struggling for some peace for the next few weeks

[AnnieBrooke]

Although your first ultrasound was too late to count on to be able to assess when conception was with pinpoint accuracy, your next ultrasound also backed up the June 23 estimated conception date, suggesting the baby is growing at an average rate (not faster or slower than average).  If so, you could possibly trust the June 23 conception date, and rule out the guy on June 30.  Are you intending to do a DNA test only after the baby comes, I assume?  If so, you can be cautiously optimistic that the baby didn't come from the sex on the 30th.

[AnnieBrooke]

By cautiously optimistic, I'm saying, still do the DNA test.  It is too important to know for sure, don't forgo the test.  But don't drive yourself nuts in the meantime, it's not worth it.  

[purplewf22]

The test will be done, for both of our peace of minds. We opted out of the amnio so therefore did not go forward with the testing that way either. I felt like I knew the week of the 4th when we were on vacation and I had one drink and almost immediately felt nauseous (heavy drinker, uncommon side effect for a spiked lemonade) and then the following week at conference I was pure exhausted and constantly having to leave class to use the restroom. Just trying to ease my mind still as we have 6 weeks and 2 days to the due date. Thank you for your quick response!

[purplewf22]

But yes, both US said the same thing and even though it is not completely accurate either, my fundal height has matched perfectly minus one appointment when my fluid was low and I was then measuring 2 weeks behind.

[AnnieBrooke]

Frankly, in my opinion the fundal-height measurement is not that helpful, it's so variable and has almost been made obsolete by ultrasounds.  But you sound like you're on the right track and the assumptions made are correct.  It's just that your dates are a little too close for comfort, so you do need to know for sure.  Fairness to everyone (you, the baby, and the guys) dictates the need to know, and of course you want to put the question to rest for good.

I wasn't talking about amniocentesis when I mentioned DNA testing. There are blood tests (from the mom's arm and the dad from a swab) that can be done before the baby is born, that are noninvasive. But they are so expensive that only when someone has a pretty serious need to know, do they do them.

Try to relax, get your test at the time, and let it all be a thing of the past after that.