paranoid!!!😩

Hey guys sooo , I had sex with my boyfriend about 3 weeks ago maybe on the 3rd and 4th and we didn't use a condom both times. I started my period literally the day we had sex like later that morning. I'm super paranoid because I been really up and down with my mood and it's like I been nauseous like everyday almost for the whole day I just don't even wanna eat . Is it possible I'm pregnant? Or no? I like have sooo many symptoms but I don't know