Bleeding while on progesterone????? why?

I was diagnosed PCOS in dec 03. In June 06 I had a baby. Since she was born, I never stopped bleeding. the drs put me on birth control and it finally haulted. My husband and I decided we want another baby. SO the dr said to stop taking my pills after i finish the pack. My period came, and I continued bleeding. I bleed for about 10 days, stop for about 4, then go for another 10 days, stop for 4 and so on. My gyno screened my for endometrial cancer - it came back normal. And she started me on progesterone for 10 days. Im on day 9 and my bleeding has STILL NOT STOPPED. She said she doesnt know why. So shes giving me another 10 day supply of progesterone by a different brand. What in the world is this? Does anyone have anything they can input? I go back this coming friday for a check up. I just dont know whats wrong with my body. Why cant I quit bleeding??? Anyone have anything? Any ideas? Anything? please....? :(

I guess someone will ask, so I'll answer it now. Im 25 years old, weigh 120, eat healthy and am 5'2" tall. Someone always asks, so Im just saying it.