Before I started taking the pill, my periods were always exactly 30 days apart. I started taking progesterone-only pills (I have migraines, so I can't take the excess estrogen) about two months ago, I had two periods in one month, which happened this month too. I know that the progesterone can cause spotting mid-cycle, but it's a full, 7-day period. How much blood is normal between periods? Thanks :-)