So, erm, how long does sperm live for?

[BotBotticelli]

Once it's inside you, like??

DTD on cycle day 10 this month, normally get LH surge around day 15...that's too early to DTD and get pregnant, right??

Nope 3-5 days maybe even up to 7

Up to 7 days.

And it's anecdotal I know, but according to temp chart and cervical mucus, I reliably ovulate on around day 14. Both of my pregnancies we have DTD on day 10, and going by dating scans, have conceived on day 10 or thereabouts.

After ovulation, the egg only survives around 24 hours. So it's much less risky to take chances with contraception between ovulation and period than it is between period and ovulation ...