Our son was a surprise. We never talked about whether we wanted to have kids or not, but were more like, if it happens, it happens. If it doesn't, oh well. I would have been a happy person, either way.
Sometimes I feel a pang when I see siblings, but decided not to have another for several reasons:
-Never felt compelled to bring another personality into the world. I'd only have another for our son to have a companion, but that didn't feel like a good enough reason.
-Our son came out perfect. Everything was easy with him--the pregnancy, birth, sleep. There's no way I'd get lucky like that again. I was worried with the second child we'd encounter a lot more hurdles/potential regrets.
-I want to retire early. If we had another I'd feel more pressure to keep working. For now, it's nice to know I can stop working and spend time with the child I do have when he's younger.
-We do not have family help close by. No joke, literally every family I know who has multiple kids is not doing it on their own. They all have grandparents close by to help.