I am in a similar position OP and have found this thread useful so thanks for starting it!
I always assumed I would have kids, grew up wanting them, not able to imagine life without them etc. Then my first couple of friends had kids, I saw the reality and it completely put me off! Now happily married and DH and I are trying to work out what to do (of course we may have fertility issues we don’t know about as we haven’t started trying yet).
Despite some people being upset by her posts I’ve actually found @MinnieMous3 ‘s posts helpful as I think the option of having just one child isn’t really talked about much. It’s always “do you want kids? plural. And if you were to say “I just want one”, lots of people would respond “oh but won’t they be lonely?!”
I think it could actually be a good option for us as I think the real difficulties with parenting come when you have your second child - that’s when I’ve noticed women’s careers seem to take a real nosedive and I’ve read it’s statistically when most marriages are most likely to fail. Also, it just sounds messy and noisy and complicated to me, as well as dragging the pain out for longer. Whereas I think I’d be ok going through pregnancy, childbirth and the newborn stage if I knew it was just that one time and single children don’t seem to bring the mayhem with them that two or more do.
Also I know sooo many people who don’t get on with or aren’t close to their siblings so I never get why it’s trotted out that kids just HAVE to have a sibling! What, so they can practice arguing all the time at home? 
Still on the fence but may think about just having the one, so thanks for your input @minnie (and for those of you she upset; this is a thread about childfree people not about infertility so you were actually just derailing the thread for your own purposes)