I am in my upper thirties, too. Will turn 38 this month. Simone and I are not sure either if we want to have a second child. In one way we say "yes" and then we say "no" again when drowning in stress and work. I just started a new job about 2.5 months ago and I also take care of our own small business. There are just not enough hours in any given day for a second baby.
Christoph