Late period

Hey anyone reading this, so my period is late. It's not the fist time this has happened. But this time it's a bit different. Every once in a while I'll skip a month but it always comes back. My period was always irregular growing up. And it finally regulated once I was around 21. Well, this time around my last period was Dec 16-19. My period last 3 to 4 usually. For January I didn't bleed or spot at all. This month I had spotting on and off for 3/4 days. It came about once I had sex a few days ago. It's only ever been brown spotting when I wipe. Not even enough to leak on a panty liner. I'll "spot" for a couple of hours then it'll go away. I did take a PT that I had laying around but it came back negative. I am also planning on going to the doctor's at the end of the month if it doesn't come at all. My boyfriend and I don't use condoms and he never pulls out. But honestly, I don't want to get my hopes up. I want to know if anyone else has had any similar experiences that was not pregnancy.