Could I be pregnant or period? Helppp😫

I’m completely stressed out. So the first day of my last period was December 3 and it only lasted 2 days however I’ve been keeping track of my periods with this app and it says there is 2 days til I’m supposed to start but I haven’t had any cramping and yesterday my boyfriend told me that I was bleeding or something and I was like no can’t be true and he was like look but it wasn’t bright red it was a very light brown(which I’ve never had) ... but I haven’t been cramping so I was confused but however I have been experiencing that, sore nipples and heavier breast, dizziness, very thirsty, I eat more than I usually do, very emotional, back pain, very exhausted usually, but I have taken a clear blue pregnancy test and it still says negative... could this just be my period or implantation? Advice please help 😫