Very confused. Need opinions.

So my period was two days late. I felt funny for at least three days prior and took 3 bfn. Well I started at around 9 this morning and it looks almost over already. Less than a full day? That's really not normal. It's already a dark almost brownish color and not bright at all. It was maybe a little over half a pad to a pads worth. I'm very confused. It's usually heavier,on time and at least 4 days.