honey, you should have started with that, that sound suspiciously like good news!
and falling down the stairs would not have made any difference to fertility/conception/embryo - although it is a shock to your system, so could have delayed your ovulation!
(basically if anything stressful happens to you, even things like travelling or taking an exam, your body thinks " hang on, that's not good, let's just delay the egg/s, coz this would not be an optimal time for pregnancy, future mum is a bit preoccupied!" hence the common wisdom, that stress is the biggest enemy when TTC!!!!!)
with my DS5 we had our night time fun - the next day I kid you not I was very nauseous and just knew it!
with DS3 I had bad stomach cramps within half an hour of sex and the cramps/period like pain lasted for 2 weeks!
it turned out the timing was perfect (by accident mind you, DS was only 8 months and I was still bf, so didn't even have periods yet!) and the pain was due to the uterine cramps, which often mark the early weeks of pregnancy as the uterine lining grows thick, stretching the organ.
(I actually had that pain with DS5 really badly, then a bit milder with DD)
any other questions?
I'm now very interested to see if you are pg or not - don't promise me, but let me know if you remember! 