OK so I'm on a 28 day cycle like clock work. I had sex the day before I was scheduled to have my period and then my period was 4 days late... what the heck, any ideas? Could I be pregnant?

You had your period? Most likely you are not, but you will have to wait until your next period is due before testing.

Periods even clock work ones get off sometimes, having sex and perhaps the stress could cause it to be late. If you had it, and it was just late most likely no you are not pregnant,

Really to be 100 percent sure, just have to wait till next month and see if you get that period or not