A littler confused.

unknown

So I’m sexually active but I always use protection ( condoms and a plan B if needed.) I haven’t had sex on 3 months (August 26) and I took a test two weeks after and it was negative. The most recent cycle is four days late and hasn’t come. I have not had any symptoms of pregnancy but I’m scared my period is usually a day late at most but never four. What should I do?