late period and bad cramps

So my period is a couple days late and it's usually an exact cycle I get it the same time each month but this month It hasn't. It's never been late. I had protected sex a couple weeks ago but he didn't cum so I don't think I could be pregnant. I'm also getting really bad cramps and headaches and Ive been bloated like I always am during my period. If someone can tell me what's going on so I'm not all freaked out about possibly being pregnant at 15 That would be amazing