Why got my period late?

I was suppose to start 5 days ago but nothing I had no cramping no loss of appetite or any of my PMS symptoms. I had intercourse yesterday and I woke up this morning with little bit of blood like I'm about to start. But why so late? Could the intercourse have triggered the bleeding? I'm regular and usually heavy but this month I guess came late
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+1 y
Scratch that I had little bit of cramping during the days I was suppose to start my period but wasn't bad like I normally do.
Why got my period late?
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