Community post

unless you take daily temperature or use ovulation prediction kit (that is what women do who try to conceive or not to conceive) you cannot know at all when you ovulated.
you can read the wikipedia article about the menstrual cycle.
normally, the luteal phase (the second half of the cycle) is 14 days long. so if your cycle is usually 28 days you ovulate on day 14 on your cycle. some women ovulate somewhat earlier or later though.
your fertile days are the three days before your ovulation (the maximum lifetime of the sperm), the ovulation day, and one day after (the maximum lifetime of the egg). (5 days total)
for example
if your LMP was Nov. 11, then you may have ovulated on Nov. 25 when you had sex, and in this case there is some chance (say 30%) the egg got fertilized. in this case if your period does not come on Dec. 9 you can take a hpt and see.

PS if your LMP was Nov. 11 and your ovulation was on Nov. 25 then today you would be 7 dpo (too early to test or feel anything). If you ovulated later (say Nov. 27) you still could be pregnant, but then you are only 5 dpo.

I highly recommend the Ovia app on your phone. Plug in your period information and it will guess when your ovulation zone was/is. The only real way to know exactly when you ovulated was if you were doing ovulation strips or doing the temperature method, etc.