3 days late

I'm 3 days late for my period but I've taken a hpt and it came out negative. (And yes I took it first thing in the morning.) My breast have not been tender or sore like they normally are before my period and I've had cm discharge like crazy. I've had really bad heartburn the past 2 days and foods that I normally like don't taste good or make me nauseous. Could I still be pregnant or am I testing too early? I'm so lost right now so please help.