Birth control makes my periods irregular. Does that mean it’s less effective?

Before birth control my periods were super regular. Now they are all over the place. My periods come at any time. It can be in the beginning, middle, or end of the pack it doesn’t matter. They sometimes come every two weeks and sometimes longer. I NEVER skip pills and make sure I take them at the same time (+ - an hour or two) every day. It’s super annoying but I’m worried that means the birth control isn’t working like it should and I’m not protected. Anybody have the same experience?