Advice? Period Late!

Hey gals,
So I just wanted some advice. My period is late! & I took a Preg. Test when I was 4 days late & it came out negative & I'm now 11 days late and idk what to think? Or what to do? Should I take another test? 
My bf & I haven't had full on sex. And he hasn't cum near my girl. So my question is why is my period 90% of the time late?!
Has anyone else experienced something like this? If so what happened?
Am I just being paranoid? (Because my bf thinks I'm very paranoid) 
How can I make it regular? W.o BC?