What’s really the chances of having a period while pregnant?

Em

I had sex december 6th, and started having pregnancy symptoms so I took a test and walked away and came back and it had a faint line but I am not sure how long I was gone, it might have been over the 7 min mark. And my period started yesterday I have really heavy bleeding and heavy cramps, but my partner is insisting I probably am pregnant and are just having a period while pregnant. What’s the probability of that? thanks for your answers ❤️