Firstly, intercourse around the time of menstruation
is safe. Added to this, you have taken the emergency pill and this gives you added protection. Also, emergency pill contains high doses of hormone and this disrupts the normal hormonal
milieu and causes breakthrough bleed. You may be having your normal menstrual period added to this. Though your chances of conception are almost nil, if you are still worried, you may go for the blood test
. Hope this information is useful. Take care.