DD was at least 14 months before I discovered I could look at a newborn baby and think warm thoughts instead of 'OMG, I am soooo not going there again', LOL!
At 18 months, a little sooner than we'd initially thought, we decided to TTC #2 - our last. I didn't suffer from PND, but I was a very anxious parent with a fairly wakeful and unsettled child, so it was only when all of that settled down that I even entertained the thought of a second. I am still a bit scared about looking after the two of them (and OMG - bubs is going to be here all too soon, LOL!) but I feel now that I will be able to cope. Any earlier, and I don't think I would've.
You're so normal, mate. Enjoy your little one and leave the future to the future