(Context: Am dad. Love kids. Find parenting super tough. No regrets.)
How's this for a rule of thumb: if you can be happy without having kids, don't have kids. They're very hard work, expensive, and often bad for your mental health. But, if like a lot of people you know you will always be sad if you don't have kids, have as few as you need to scratch the itch.
I might go the other way: if you can’t be happy without kids, maybe don’t have them. I love my kids, but they’re not some magical antidote to sadness or malaise and trying to raise them while you have underlying issues of your own is likely to be brutal. (Naturally, if you’re “happy except want kids”, this doesn’t apply.)
I’m glad I took the time to find out what I wanted to be before that was just “a good dad”. I feel fortunate that I found that out, met my wife, and we were able to have healthy kids at the tail end of our 30s.
How's this for a rule of thumb: if you can be happy without having kids, don't have kids. They're very hard work, expensive, and often bad for your mental health. But, if like a lot of people you know you will always be sad if you don't have kids, have as few as you need to scratch the itch.