When will the spotting/breakthrough bleeding end?

This is now my third month taking birth control. After my first pack, I wanted skip my period for my birthday, so I skipped the sugar pills and went straight to my second pack and had no period. When it came time for my to start my third pack, I again skipped the sugar pills and went straight to the third pack. But this time, I did start my period. That was last Wednesday. This is now the 10th day that I have experienced bleeding. The last 5 or 6 days it has been really light, like spotting, and is not constant. I was just wondering if this is normal and if it's possible to estimate how long this spotting will continue? It's very annoying!