Read the book Taking Charge of your Fertility. All you have to do is check your temp first thing in the morning and your cervix once day for position and feel (hard, soft, medium), as well as cervical fluid. Every day. And record it on a chart. (I do it online, on their website.) You will ovulate around the time you have eggwhite-quality cervical fluid (it's stretchy) and your temp jumps up above a certain line (based on your average temp that cycle, hence the need to temp every day). Read the book.
Sperm can potentially survive 5 days inside you (3 is more likely, and it can be only hours if your cervical fluid is not conducive to fertility), and an egg only lives 24 hours if not fertilized. Most people count 48 hours just in case of a second ovulation the next day. So you're potentially fertile (as in sperm can survive in you long enough to potentially fertilize an egg) from 5 days before ovulation until 2 days after
at 12:10 AM on Jun. 28, 2011