Help please!

Giselle
I've been trying ttc for 4 years and during those years I had 3 mc and 1 ectopic and my right tube has been removed. This month my doctor prescribed me progesterone vaginal and on my 6, 7, 8 DPO I tested and got faint positive. Today is DPO 12 and I decided to test again and it came back negative. I'm confused. Did anyone has similar story? Am I still pregnant?