Period or early pregnancy?

Hi there I've been TTC for a while now and according to glow my period was due today and I've had spotting that isn't getting on my pad but i can only see when I wipe down there. Is this an early pregnancy sign because usually on my first day of my period my cramps are unbearable and I'm usually in so much pain I can't walk and my flow is extremely heavy but it's very bearable and just strange.. anyone experience this and then get a BFP?