Is my period just late?

I'm 15. I had sex for the first time at the beging of this month. I was suppose to start my period a day or two ago but im really stressed out and I dont know if im late because of stress or what. I mean we used a condom and everthing ... this is kinda embarassing but he also said he wasnt finished... if you get what I mean. I dont know what to do or if im just stressing m self out because I've had cramps a few times already. ... am I jsut late?

it might be an irregular period
or you can use a preg. test
to find out