A few questions about how this works?

I had sex 5 days ago, and I'm supposed to have my period next week. Is it possible that I can have my period at its regular time and still be pregnant? Or is it the next one after that I should be keeping track of? This is kind of all new to me. I should add that me and my boyfriend both got drunk at a wedding, I'm not on birth control, and neither of us remember if we used a condom (please no harsh comments; I'm still putting myself and him down over all of this. I'm terrified that I might be).