Hi, Sarah, I agree with the above poster that you have nothing to worry about. If an embryo does not implant in the uterus by about day 10 after sperm meets egg, it doesn't have the nutrients it needs to go on, and it fades away. You will not have had some secret embryo floating around for months and then implanting. It is medically impossible. So, no worries. Congratulations on the twins!
It was a true period in July because if you have gotten pregnant in July that means you would be due in April like me! Sperm can only survive 5 days inside you some 3 days! If your due till June you for sure got pregnant in September, I would trust your early it can only be off 7+/- days which it still gives September dates! You had two periods in between I wouldn’t worry at all! You can use this calculator! https://www.calculator.net/pregnancy-conception-calculator.html?ccalcmethod=due+date&dueDateDay=06%2F08%2F2022&cLastPeriodDay=08%2F25%2F2021&cCycleLength=28&cUltrasoundDate=02%2F01%2F2022&cUltrasoundWeek=22&cUltrasoundDay=6&printit=0&x=136&y=29
I say all of this because I’m in a similar situation I only had one period in between and I’m freaking out!