Hi mama! Based sa timeline mo, if your last period was October 6-9 and you're now 8 weeks 6 days pregnant (as of Dec 3), then yes, you most likely got pregnant around late September or early October, that fertile window is usually around 5-7 days bago mag-ovulate, so pwede around end of September or first week of October depende sa cycle mo. The reason your belly showed early at 1 month could be kasi second pregnancy mo na, so mas mabilis lumaki ang uterus compared sa first time, that's totally normal! But honestly, para sure sa exact conception date and kung consistent lahat ng dates, better to ask your OB during your next checkup kasi sila lang ang makikita sa ultrasound kung tama talaga ang dating mo.