T.M.
This is a point of contention in my marriage. I am an only child...my husband is the baby of 3. He always felt bullied, ignored, and shorted as a kid. There wasn't a lot of money and by the time it came down to him, there wasn't a lot left. His siblings got to do sports, and he didn't. That sort of thing. His siblings, of course, say he was the baby who got away with everything. His dad actually had to call the cops on his sister because she was beating him so much. So he wants our 2 y.o daughter to be an only child so he can "give her the world" and not make her have to share us, or her things, or anything!
My story is pretty different. I am an only child (I have 1/2 siblings who live in a different state and are much much older) so my point of view is that of a lonely only. And it was, lonely. My childhood is marked by what program on television I was watching at the time. I had trouble in school with talking too much because I was alone so much with no one to talk to that when I got to school, I couldn't shut my mouth. I admittedly am pretty spoiled (although not bratty). I had things and got to do pretty much anything I wanted within reason. I had diamonds and cars, and spending money but guess what? I was still lonely. We weren't rich growing up but since I was the only one my parents could splurge. I never had problem with sharing or anything like that, and I think I did ok, but I was more lonely than anything.
So I want 2...my husband wants 1.
It has everything to do with your parenting. My parents could have made a concerted effort to be home more, do stuff with me, and create an extended family through friends, and I'm sure I would not have been so lonely. My husbands parents could have divided equally, and enforced house rules of respect and kindness and I'm sure he wouldn't have felt left out and abused. There are perks to both.....
If you both want more, I would say stop trying and let it happen when it happens if it happens. Sometimes when you stop stressing and "trying" then it happens.
Happy baby makin' or just practicing :P