Having a second child, or not

Luanda writes:

"I'm having the hardest time deciding if I want a second child. I'm an only child (a happy one), but always wanted to have a big family. It's been taking us (specially me) a while to decide because I had a scary pregnancy the first time with Alice involving pre-eclampsia and two months of bed rest. Not fun. 

I'm coming close to deadline and after seeing different doctors and finally deciding to go through another possible high risk pregnancy, I find myself with another issue.

I'm feeling lazy. Alice is already 3.5 and life is pretty peaceful. The thought of starting all over again haunts me.  As much as I always wanted a second, I'm also concerned of how that would impact Alice. I would be so sad if she didn't accept the fact that she is not the center of our world anymore. We have such a close relationship, I'm afraid that a second child at this stage would create a distance between us. She's already at an age where she is used to being an only child and she would be 4+ if we decide to try for another one soon. On the other hand I see the age difference as an advantage for all of us. I could never imagine myself having two kids close in age. I would go nuts.

We're definitely not financially prepared and probably never will be, but I see the addition of another child as a desire and not a calculation. And what if having a sibling be the greatest gift to her? And I know this crazy period of baby's life goes by fast and eventually I would get my life back again. I just don't know if I want to go through it. But I'm afraid of regretting if I choose not to. I'm so on the fence. Every time I see a pregnant women or siblings getting along well my heart melts. But I love having only one child. Alice is my little sidekick.

I wished I didn't have so many concerns. I hate to over think this. I just want to come up with a decision and free myself from this subject. "

Thoughts? I know what decision I made, but the calculation isn't the same for everyone. How did you make the decision?