Late period and don’t know why PLEASE HELP.

I’m 17 almost 18 and my period is a couple days late and I don’t know why. I’ve been having major cravings the last week. (All I want to do is eat fries and ice cream). But I’ve also have the worst mixed emotions of my life. HORRIBLE. All in one hour I was mad the next pissed off then sad crying, back the to mad again, and then I finally cooled off. Yes I have been having sex but we have always used protection and I don’t use BC. So one thought is that I could be pregnant. But another thing is that I’m sick. I have a sore throat, some coughing and stuffy nose. Can being sick cause it to be late? Or is there a chance? Or is it just late? I would really appreciate your input right now!