Pcos and BC

I have been trying to Concieve i am very irregular usually have a 45 day cycle. This pass month i have been spotting for 7 weeks as of today i went to see my gyn and she prescribed me birthcontrol but my question is she told me to take 3 pills a day for three days than 2 pills a day for 2 days than continue taking one a day until I finish the pack is this safe to do???