Weird Period...

So I'm on the third day of my period (my periods only last four days) and I have not bled at all like I normally do. I've had spotting the past three days, and all my usual symptoms (cramps, headache, backache, insomnia, mood swings), but no bleeding, no clots, nothing! Also my cervix hasn't dropped, and isn't as firm as it should be for a period. And I'm normally a pretty heavy bleeder to begin with, so this has been extra confusing. Is this even a period??