help me

Okay I don't know if this is normal or not because I lost my mum and I'm 16 and I won't speak to my dad about this stuff so can someone help? Anyways so I was meant to get my period yesterday & my nipples have been hurting since Thursday. I can't pinch them with out pain but they don't hurt anymore , I had sex  over a two weeks ago with protection and he pulled out before he came. it's said my bra could be the wrong size or an infection and that people get it a week before there their periods.. Is the pain normal?
Also I keep stressing and making my self think I'm pregant because that's what people do, but i was told that stress can make your period late?
If so how long normally ?