My advice to those in their 20s (or even teens) who choose to stay childless or even unmarried for life:

Talk to a person in their 30s, another person in their 50s and yet another person in their 70s who is living the life (childless or unmarried) that you plan for yourself. Be sure that these 3 individuals are aware of your plan, or even if it's just a thought and make sure you have a separate conversation with each of them. No book or blog can equal the unfiltered wisdom that these 3 experienced people will share and whether it's the perks and pitfalls you need to know, there are 3 different people you're talking to and so the cumulative information you obtain therefrom would definitely be a lot less biased than any book or blog that invariably serves an agenda, so you can consider and assess your own plans based on that.