Does Nordette Cause Light Menstrual Bleeding?

Hi. I took Nordette as an ECP 7 hrs after unprotected sex and didn't experience any symptoms. 7 days later, I experienced heavy bleeding like my normal menstruation. It's been 3 months since then and I haven't experience any bleeding expect a very faint bleeding last month that can only be detected when I used tissue wipes. Is this the effect of ECP? Am I pregnant?