Look, OP, a certain (fairly widespread) type of person who chooses a conventional path in life, which generally involves buying property, marriage and children as key life milestones, desperately needs other people to make the same decision to shore up their life choices.
Those people are agog when they see someone make different decisions, and suspect that these people 'have it easier' than they do, and hence want to try to undermine the other person's confidence in their (often marginally) less conventional decision.
Eg. They bought a house? Oh, you're 'throwing money away' on rent or 'paying someone else's mortgage'. They've never spent more than a fortnight away from their home town? Oh, you'll regret going to live in Germany/Ghana/Ecuador because you'll miss out on all your family occasions. They got married? Oh, you'll die alone eaten by your Alsatians. They had 2 children? Oh, you'll die alone, eaten by your Alsatians (again).
Having children is the key life decision that features in this kind of mildly nosy undermining, largely because your life as a childfree person can look awfully attractive and free to someone struggling with parenting.
Basically, your decision not to have children makes them realise that they made a choice to have theirs. They didn't have to, no one made them.
Take not the slighest notice.
I was happily childfree until 40, and took not the slightest bit of notice of the people who were so certain I was going to regret not having a child. Then, within about ten minutes of me having DS, the same kind of person (essentially strangers met at other people's parties) was all about when I was having another child, and when I said I had no intention of having another, they started banging on about how selfish it was to have a 'lonely only', and how I would definitely regret that. Because to someone with three children, my very adaptable, portable one child looked 'too easy.' He travelled with us, he was cheaper in terms of childcare, he took less looking after, he moved countries with us etc etc.
I did choose to have a child in the end, and he's wonderful, and I'm glad I did. But I know perfectly well I would have been equally, though differently, contented had I continued childfree.
Don't do anything you don't want to, and don't ever do something you don't want to because someone else tells you you'll regret it later on if you don't. Good luck either way.