Deciding on another baby??

Cheryl
My Little Monkey turned Four on Friday and My Little Miss turned One on Saturday. 
Last night hubby and I had unprotected "nookie". Before we started he asked if he should use a condom (we use protection during fertile time), I said I don't know as I hadn't looked where I was in my cycle. He just said "oh well let's just see what happens". I was a bit shocked at this as we normally discuss when to start trying for another one.
Anyway, it turns out it was CD15 and now I'm stressing that I may be pregnant. We definitely want another baby, but I'm now thinking I wanna wait a bit longer as our Little Miss is still very dependent on me and very clingy still.
How or when did you decide it was time for another baby?