Baby, in reading both your questions, I have one small detail to add. You asked whether it was likely the sperm was waiting for the egg, and no, that's not likely. It's likely the egg was waiting for the sperm. But that's just "in general". In general, if the egg is waiting, you have a higher chance of conceiving a boy (male sperm swim much faster than female sperm). If the sperm was waiting for the egg, it's more likely you'll have a girl child (female sperm swim slower, but live longer and are capable of sitting there waiting for the egg). I don't know whether this is in favor of the guy you are hoping will be the father, it's all kind of confusing, but just thought I'd add that. Congrats on your pregnancy and hope all goes well for you.
Hi, Baby2021,
Thanks for writing in, here and on the other post, it helps when someone with these quandaries hears from other women besides me. lol And my answer will probably be longer than your question! (which, thank you very much for your complete and calm job of giving the pertinent facts and your concerns). The short answer is, no, you can't disregard the earlier ultrasounds, even if the later one gives you an answer that you like more. But the first guy is not ruled out either.
The growth rates of embryos and fetuses can vary: some babies grow faster than average and some grow more slowly. Because of this, early ultrasounds are often more accurate than later ones for trying to determine when conception was. (An embryo at six weeks hasn't had a lot of time to grow and diverge from the average, and a 20th-week fetus has had many weeks to develop a little faster or slower than average. In essence, the scan could measure the baby perfectly and then impute a due date from the baby's size based on the assumption the baby is growing at an average rate, when perhaps the baby is not.)
When someone has a 6th-week ultrasound and a 20th-week ultrasound that disagree, I generally counsel them to pay more attention to what the 6th-week ultrasound indicates, no matter how blurry the photograph or what the imputed motivation for the ultrasound. (And regarding that, an ultrasound is an ultrasound, and an ultrasound tech is a trained medical professional. Planned Parenthood provides women's health services for many thousands of women who don't have abortion in mind. There's no "abortion way" or "keep the baby" way to do a scan, there is just scanning the baby. If you're saying the whole place seemed unprofessional or amateurish, that's a different issue, but I'll also volunteer that hasn't been my experience with Planned Parenthood.)
This means that you really can't just disregard the 6th and 9th week ultrasounds. Unfortunately, the sex was in too close succession for any of your ultrasounds to answer the question for sure. (As I said above, the 20th-week ultrasound could be a perfect and exact picture of your baby's size and development level, but a scan can't tell if the baby has been growing a little fast.)
Here is what also could throw off your dates from the various ultrasounds just enough to be a problem when the dates of the sex are so close together. You have a regular 30-day cycle, but most calculations of this type are set up for a menstrual month of 28 days. Ovulation happens around 14 days *before* your next period is due to begin, not 14 days after your last period came. This means your ovulation will probably be a couple of days later than the average woman with a 28-day cycle. You'd have to have told your cycle length to the techs, and they would have to have had a way to compute it in, if they were the ones who gave you the possible ovulation dates. The fact that the Planned Parenthood people gave you a 15-day span between your presumed ovulation date and the first day of your last period sounds a bit like they did have this information, but it's hard to tell. (If the ultrasound techs only did your EDD's, and then you went home and used a conception calculator yourself to calculate ovulation, you will be dealing with software that uses 28-day cycles and not 30-day cycles, and again, that just won't split the kind of hairs you need to split.)
If your period began September 11, and if you always without fail have the next one in 30 days and it never, ever varies month in and month out for years, you would have expected the next one around October 10. Counting back from October 10 gives an estimated ovulation date of the 26th of September. This sounds promising for the hail Mary pass, except you don't know for sure if that period really came on September 11.
In your shoes, I'd definitely prepare to find out for sure with a DNA test -- if you have the big bucks, call Ravgen and test now with both guys. (Ravgen also has discreet testing, which helps some women a lot.) Or, when the baby comes, run a DNA test at the hospital (again, with both guys) for about a tenth of the cost. I certainly wouldn't tell one guy definitely that he is the dad and the other guy definitely he is not, until you have a DNA test for both guys in hand.
Good luck, I'm sorry that the answer isn't clearer at this point, but mercifully, it will be soon enough. And congratulations! A baby is a blessing even when we have to wait to know what we want to know.
Annie