PCOS - no period?

I was diagnosed with PCOS when I was 20,  but it wasn't too much of a problem because I wasn't trying to get pregnant at the time. Now that I'm 25, married, and ttc, I'm still struggling to get my period. My doctor has me taking 200mg of progesterone the first 10 days of the month to help me get a period. It worked the first month I was on it (March) and I bled A LOT. But after that month, I only ever spot. The spotting usually lasts about 3 days and is brown.