Periods?

Ol
Does anybody else have weird periods? I've had a period since I was 11. And it's always been regular. Every 26 days or so, I'll have a 4-6 day period. And then a few months ago, it changed. I would miss a period, then have two months of regular periods, miss another period and then have two months of regular periods again. Has anyone else experienced this? Should I be worried?