Hi Jillster, I understand exactly how you feel.
I'm 45 ( hubby is 55 ) and to be honest I'm sure I will question my choice on the odd occasion until I'm old and grey ! The trouble is, I still keep coming back to the answer that I have done the right thing for me.
As misstalia says, every life choice will be questioned at times, and let's face it this is the biggest life changing decision anyone has to make.
I'm sure I would have loved to have a bond with a child of my own, laughed, played, hugged etc. - all those soft fuzzy, romantic things that people talk about in relation to offspring.
But some parents seem to forget we have deep feelings for those we love - wether it's parents, family, close friends, - or furry friends

and having kids or not should be an informed choice, and having looked at the whole picture my choice was not.
Does it mean it was an easy choice ? no. does it mean that I won't question that choice ? of course not.
We are all intelligent forward thinking people, and as such it is only natural to question and mull over every decision we make throughout life.
I come back again to the stereotype that many parents have - if you haven't had kids you're an unhappy, unloved, miserable old prune.
The reason why I love this forum is that I don't have to try and prove to these parents that actually I love life, have fun, laugh regularly, and don't need a child to feel complete.
AND I like prunes....
So don't feel bad when these feelings bubble up. accept them, and accept yourself for the choice you've made.
That's part of the problem - society makes you feel bad for your choice.
enjoy the good things in your life.
hugs.