I have banned my close friends and family from using us as an example, as I hated the 'so and so had IVF then naturally conceived quads' type stories when I was ttc! I knew people were just being nice but it really annoyed me...
We tried for no 1 nearly 2 years (but over two years of cycles as I have a 23-25 day cycle). It started with just shagging and after 6 months got more 'technical' with taking charge of your fertility and charting and the like.
Tests after a year plus showed I was fine (possibly a bit low in progesterone, used to spot before my period) but dh had both low count and low morph (he has only one testicle due to previous testicular cancer and his oncologist suggested maybe his 'dominant' testicle had been cancerous, eg the way one ovary can release more eggs...).
We decided to skip to private IVF/icsi with the lister and got pregnant first time. I was 31 during treatment and 32 when I gave birth.
We were actually gearing up to do IVF round 2 when I got pregnant (DS had just turned 1 and I was 33). We had seen the consultant and started the ball rolling. I just needed to give up bfing and wasn't ready to. Then that miscarried and I was still bfing. Within a couple of months I was pregnant again.
This time was an utter shock. We had decided we'd love a third but no more IVF so if it happened it happened. We only shagged once (though stopped trying to prevent pregnancy last may). I'm still bfing dd (22 months). I'm 36.
My own (totally unscientific) theory is that bfing somehow helps me. I was bfing with all my natural conceptions and have never spotted once my cycles returned (around the 7-9 month mark).
I also think we were shagging too much for no 1. We'd sometimes shag twice a day which probably meant dh's sperm wasn't in great shape. Second time it was every 2-3 days (I of course knew my fertile times but never told dh). This time was just once.
Dh's theory is that fatherhood somehow boosted his testosterone and therefore improved his sperm (though when we saw our consultant at the lister a year after dc1 was born his sample was still in the ICSI realm).