So you've had your period since you had sex-- like you're currently on your period? If so, you're not pregnant.
I'm confused. Are you trying to conceive ? You're not using any protection against pregnancy so I'm just curious. Since you say that the guy pulled out I'm assuming you're not trying to get pregnant right? Condoms are cheap, if you don't like condoms then look into birth control. It will save a ton of stress and worry. Unprotected sex is a gamble and it's only a matter of time that it ends with pregnancy.
Because I'm not sure if you're on or off your period right now, if you're not having you're period and you're worried about last night then you may want to look into plan b. It's a two dosage pill a woman can take to up to 72 hours after sex in a last attempt to prevent pregnancy.