Sometimes it takes a few months for our bodies to adjust to birth control pills, especially in your case since you already have irregular periods. Keep taking the pill on a regular basis at the same time everyday and watch for breakthrough bleeding and other side effects. After the first month if you are experiencing severe side effects or you aren't happy with the pill anymore than talk to your gynecologist about it. Maybe (s)he can offer another type of pill that will be better suited to your needs. Like I mentioned earlier, it may take a few months for your body to adjust to all of these new hormones, but with time, you should be pleased with the results.