Funny story:
With my first kid, I'd been trying for 9 months, nothing. I did have I think an early pregnancy loss. Started the fertility tests, etc. Started charting. Learned that I only had a 10 day luteal phase.
After 1. 5 years, was about to start clomid + IUI, was just waiting. Had an HSG in June, right before my 35th birthday. Got the Clomid. Sadly, the "right day" in July was to be when we were on vacation, so we were postponing till August.
July 4 my friend's sister said "you are getting old!" Well, duh.
Mid-July, charting my temps, and on day 10 they take a nose-dive. Yep, as expected (but still slightly above base temp). Go out for our 9th anniversary dinner. Have two glasses of Chardonnay. Next two days same temp, doesn't drop anymore, no period as expected. Hmmm. 4th day temp goes up a lot.
Next day, Sat morn, get a + test and say "holy shit".
3 months later throw the Clomid in the trash.