Sheesh, this kicked off! I saw the other thread, too, but only read the first page.
I'm not unlike you, @InAMess2023 (though more than twice your age now). I expected to have children and wanted to, but was NEVER broody in the way some women are. My career was important so I took the pill until I was 30. Then switched to a diaphragm. I thought I was brilliant at contraception, as didn't get pregnant until I was in a long-term relationship ... when I miscarried again, and again, at least 5 times and possibly more. Then found out I have PCOS, which explained quite a few things.
By that time, several of my friends had been through IVF and I was adamant I didn't want it. The strain it put on their bodies, personalities and relationships was horrendous. I just didn't want kids that badly.
I was still loving my career and being able to do all the extra time hosting clients in the evenings, going to conferences and so forth. The relationship broke down. We'd been really good at travelling together but I didn't miss a beat, travelling by myself and going to work abroad for a few years.
I bought a lot of lovely things, ate wonderful food and so on, because my money was all mine and so was my time. I married another dickhead and we talked about adoption; luckily it didn't last long so we never subjected a child to yet another trauma. Now I'm both single and childfree. That's the way it's going to stay.
It's no big deal, imo. Unless you're filthy rich, there's a trade-off for reproduction. Kids cost a lot of money and time; without them you have more independence, more freedom of choice. I am selfish because I can be, though that's the wrong word: I am self-reliant. Selfish implies uncaring - it should be obvious that childfree people can choose who to care about, and how much, in ways that parents can't.