Hello po mga mommy! I just wanted to ask something. My last mens is august 18-24 and umuwi po hubby

Ko last august 28. I had trans v yesterday and it says that i’m 8w and 1d pregnant. I’m so confused because based on my calculation I’m pregnant 7w and 5d only if he got me pregnant last august 28. I just wanted to know if accurate poba ang trans v as age po ni baby. Tia po .