You can't live like a 20 year old in your 40s or 50s, it really does look tragic.
I don't know what you mean by "living like a 20 year old", yes ok 18-21 is pretty care free these days, was for me and I assume it was for the OP's daughter as I believe she is older than that now. But I don't know many people living like a 20 year old when 21-30. With or without marriage I would have been working towards my career, most people I know were working and living independently, so finances will inevitably be a part of life in 20s for most people.
Having fun "before" kids is a weird thing to say, maybe your version of fun is different to mine, maybe I'm just "tragic", but I've been able to carry on doing what I've wanted to do with a family. I have a lot of family support, because they're young too, funnily enough.
As for relationships, I fell in love at 17, I can't help that. I wasn't going to end a relationship with someone I connect with on every level just because I was young. We knew the odds were against us at a young age which was why we made sure we didn't hold each other back, I went to university hundreds of miles away, studied abroad, he joined a career that did (and still does) take him away for months at a time. We grew up together as opposed to apart. I can't imagine ever regretting for a second not being single in my 20s to shag around because I have been fulfilled on every level. If we eventually grow apart and split, that's fine, that's life, it doesn't change the brilliant time we have had in our 20s and 30s.
I just find it odd that people who are older and supposedly more "experienced" can come across much more ignorant and not understanding that different people experience fulfilment in different ways. There is no one set way of living this life. I'm really pleased you are happy with the choices you've made and how your life has panned out, but surely you understand one size doesn't fit all.