Advice?? Scared for baby

So my first scan they gave me a due date 27th of September but online says 21st of September or 18th anyways at my 20week scan he was measuring nearly 2weeks over when he was just meant to be 20 weeks he was measuring 21 weeks and 5 days which if u calculate it that’s more closer to the 18th due date so anyways I ended up getting a growth scan and he was measuring still nearly 2 weeks over and 6lbs 1oz at 34 weeks ! So your probably just thinking he’s a chunky baby he will be fine come when he’s ready right?? Well my mum has never being able to go into labour natural (neither has my grandma) so I’m panicking because they won’t take my concerns serious and they say “we never worry about big babies only small” well I’m worried because they won’t be inducing me until I’m 42 weeks ... but when I’m “42 weeks” I won’t actually be 42 weeks because my due date was wrong in the first place ! They aren’t worried but I am leaving a baby that long can make it such high risk for being still born or for the shoulder to get cut or a need for an emergency c-section

I don’t know what to do it’s so risky for my baby to go to 42 weeks but no one is taking me seriously!!