Is there a chance?

Is there any way you could have a period and still be pregnant? Let me explain, ever since I started my period it’s only ever lasted 5 days not a day short or over. This month was my second month on metformin (I have PCOS but have regular periods and 37 day cycle on the dot) and my period was lighter than usual and only lasted 4 days? I’m having breast pains still, I’m moody and sobby, and slight cramping. Idk what’s going on but is there a chance I could be pregnant?