Could I be?

Im 20 years old. I had sex with my boyfriend, twice, a day before my fertility window. We dont have sex offten, every once and a while. Last night I had some uncomfortable cramps that i usually only get when my period comes. Could I be pregnant? Could that have been implantation cramping?

Please tell me what you think. When should I worry or take a test to see? I would want to know as soon as possible.