confused asf

if my scan showed GA 8 weeks 2 days on exactly December 1st does that mean i conceived in October ? my lmp is irregular and was september 10 and irregular so i measured 3 weeks behind. has anyone baby been healthy after that. i’m getting induction on tuesday because she has no signs of wanting to come out. also since i’m 40+5 today wouldn’t i technically be 38+5 today ? like why do they add the 2 weeks if i had no period and said that my GA was 8 weeks if that’s actually 6 weeks. doesn’t that make me technically not due on july 11 ?