I think I'm pregnant?

My period is 7 days late. Usually it is on time but this time, it's not. My ex boyfriend and I had sex about a month ago, so if I am pregnant, I should be showing at least a tiny bit. I haven't got any of the symptoms of pregnancy, my stomach is still slim as normal, someone please help. I will take a test soon, I just need some advice of whether or not I am pregnant...