Ready I have been feeling the same way. Loved pregnancy, has a very quick straightforward labour, back in pre-pregnancy clothes, adorable, gorgeous baby who (usually) feeds every 3-4 hours and doesn't cry without a cause (wind, hungry etc). So I know I am incredibly lucky.
And yet I have been wondering whether I would do it again.
Likewise the trauma of birth - even though was straightforward, natural delivery - has really stayed with me. Not sure I want to feel that way again (would almost certainly take more drugs if I ever did do it again!)
And the sleep deprivation is so much more brutal than I imagined. Half the time the tiredness is almost physically painful.
Like you I had a demanding, professional job - I am used to my fair share of late night, high stress situations. But the total lack of control makes this so much harder than anything I have done before.
When I look at S I melt. And it is hard to imagine not giving him siblings (I have four), but I do wondered whether I could get through it all again, this time with another child to look after as well...