Serennos - when dh was born, mil had mild grumbling backache up to the start of the second stage, which lasted around an hour. I've heard of other people having labours like that too.
At least when the baby comes, you aren't going to have someone's hands in your mouth (though you will occasionally have someone's hand in another orifice), so you will at least be able to articulate when it hurts. You'll also know what pain relief is available, and be able to ask for what you think will help.
It did hurt when I gave birth, and I had long labours, but I did it three times, which says something.
FWIW, I looooove the gas and air. My only complaint about it is that they wouldn't let me take it home from the hospital - I reckon a few deep breaths of gas and air would have helped a whole lot when it came to dealing with the terrible twos, or grumpy teenagers etc etc!
Good luck for 15 weeks hence, and I have to say that I loved your post - especially the last sentence.