I always wanted more than one. Didn't know how many exactly but never envisaged myself with only one child. I veered from 2 to 5 and in between!
I had a sister growing up who was my best friend, we lived constantly in an imaginary world together and it was such amazing fun, I wanted my kids to have that experience.
Then I split up with DS1's dad when he was 1, so no close siblings for him. I wanted him to have one so much I even considered getting pregnant on purpose when I knew I was leaving but I didn't entertain that thought very long thankfully.
Having had DS1 as an only child for his first 10 years it confirmed everything to me - having one child is a very different experience and a very specific kind of family setup. It's great for lots of people, there are many upsides, but it wasn't for me. I never liked it. I found it too intense, DS1 is incredibly social and needs to be around other kids. He would have done so much better with a sibling to play with.
I still wanted another. Because I was with someone new and we wanted to have children together. Because I wanted to see what the differences between new baby and DS1 would be. Because I wanted to expand our family. Because I wanted a fuller house for things like Christmas. Because I enjoy the challenge of having different children at different ages, it makes me feel less intense about the phase either if them is in, it gives you more perspective.
We eventually had DS2 when DS1 was 10. I've just found out I'm expecting DC3 with a more typical age gap this time and I'm thrilled! I can't wait to see how they all interact but especially the two who are closer in age. And all the other things apply again as well.
Also I just wanted to do it all again (both times) - pregnancy, birth (less enthused this time), newborn bit, seeing them grow up. I love it.
I doubt we will have more than 3 because it feels like 3 is pushing it really to begin with for us, but I am glad we didn't stop at DS2.