When did you know you were pregnant?

Hi ladies I was wondering how long did it take you to find out that you were pregnant? I'm late on my period for 5 days now I took 2 pregnancy tests yesterday it came back negative is it possible that I could still be positive? I have been feeling a little bit nausea not much also some stomach pains but don't have really any symptoms just wondering if I should wait awhile and the res test to make sure??