Ermmm..what is going on?

So I'm assuming when I bled last is was AF, but I'm not too sure. My periods are always at least 4 days, heavy flow, terrible cramping, and no other symptoms. This time it's what I think was 2 days (give or take a day because I don't know if what I think is spotting is actual spotting), extremely light for me but still red, just slight cramping, and super sensitive breasts..because it's red I'm assuming I'm not pregnant, but is it possible? Before this my last was 1/18