If you are ovulating, then you have a chance to conceive. Women with PCOS usually have irregular cycles because they do no ovulate. Are you sure that you have ovulated? If so, how did you identify ovulation? If you've used ovulation predictor kits, you should know that in case of PCOS there could be false positive results. If progesterone is detected in your blood then you have had ovulation. Low progesterone, due to yellow body failure, may cause spotting but that has to be confirmed by measuring the progesterone and estrogen levels in the blood. The spotting that you are experiencing could be only a period. Other reasons for spotting (infection, tumors) have to be checked out by your gynecologist.