oaky i already have a 2year old daughter, when i was pregnant with her i didnt find out until i was 4months. because my periodds are irregular and i kept getting them for the first 3mnths i was pregnant.

my boyfriend and i had sex last week and messed around and now there's a chance i could very well be with child. my question is how long after having sex can i wait until i can take a pregnancy test that will read accurate? because i'm afraid if i wait until my missed period that it'll be too late.