Can you get pregnant a day before your period?

What are the chances? I know they could be low. I ovulated December 4th of last month and this month i start on the 6th. Had sex on the 24th and got my period the 25th. Period was normal lasted 6 days but last Saturday i noticed 3 dots of light blood. Happened 2 times on same day when i would wiped again there was nothing. Been nauseous, moody, with more appetite, breast are more tender with green viens and urinating more. My next period is not even close due. I'm very confused.