What could this be?

I am BF my son and on a single hormone birth control pill. My son is 9 1/2 months old and I have not had a period, which Ive been told is perfectly normal. Well, the last couple weeks Ive been have very few pregnancy symptoms, not a whole lot but a few. The last couple days, Ive been getting some cramps that have been really uncomfortable. I take pregnancy tests every couple weeks just to be sure, since I dont have periods. I took a pregnancy test yesterday and it was negative just like all the others. But this morning at about 4am, I got up to go pee and I was doing some light bleeding and it was kinda mucousy(sp?). When I got up this morning, I am still lightly bleeding/mucousing but it is only when I pee, I dont need a pad or anything.

What could this be? Am I finally having a visit from AF? Am I miscarring(sp?)? Is it implantation bleeding? Or is it something else? What is going on?

TIA