Has anybody ever had heavy breakthrough bleeding, with dark red blood and clots, then found out they were pregnant?

I *thought* I had a chemical pregnancy last cycle because I had the common pink/white discharge (which I've never had before) then I started bleeding heavily, dark red blood with some clots, then the blood turned so black it was almost black. It lasted about 3-4 days (which my period lasts 7, on the dot) and it came a couple days earlier then my expected period. Well, this cycle me and SO decided to try again & I'm 10 dpo, I'm having severe pangs of nausea and fatigue, along with sore nipples, not breats.. which is VERY odd. Nothing in my diet has changed or anything. Do you think maybe I could've concieved last cycle & just had breakthrough bleeding and mistook it for my period from a chemical pregnancy? I ask because I don't have insurance to waste on lab blood tests. Is this possible ?