Maz, I don't think it ever goes away, we just learn to live with it you know?? Pretty much every friend I have that has completed their family feels this way.

We can't go on having babies forever, so I guess at some point we all draw the line and slowly, slowly come around to the idea

Maybe try to see the more positives aspects of not having any more - like your weight loss journey (I cannot believe you've lost 7kg already! You're a machine woman!), looking forward to more time for yourself and your DH, plan a holiday or two etc etc. That's what I'd started doing before i fell prg again and thought there would be no more for me, and it did help a little.