I use birth control pills and my period is irregular and weak anyway. and it takes for more then ten days.what s wrong with me?

Pill side effects: In the first 1-3 months after starting birth control pills, irregular bleeding (termed "breakthrough bleeding" is common. For almost everyone, periods become very regular and predictable after that time. Write down the dates of bleeding, keep taking the pill at the same time daily (missed pills can cause irregular bleeding), and see your doctor if it persists beyond 3 months.