[Greenie]

From what you've said, it doesn't sound like there is anything significant that's up, unless your periods are very heavy, painful or long in duration as well as the irregularity. Irregular periods can be a result of changes in excersise or eating patterns, medication or stress levels. Though seeing as it is becoming a nuisance and it has been on your mind enough to write this here, I'd say going to a doctor sounds like a good idea.