Can sex make your period late?

My period is 8 days late. I have some symptoms of pregnancy although the test I took yesterday morning said negative. 3 months ago I had sex with this guy and my period was 10 days late but the test said negative. So I went out drinking with my friends on our vacation. Few days later I got my period. Next month we didn't have sex at all and my period was on time. We had sex about 3 weeks ago and now my period is super late again. Someone please tell me what's going on! 😕