Period question that i need help on?

Im 21 and have had regular kinda heavy periods that last 5-6 days since i was 12 and the past 2 months iv hardly had a period like that its been extremely light kind of like spotty and would last 2-3 days and this month so far i have not had one yet and i think i was due at least by the 24th cause last month i started the 24th and usually every 23 days or so i start again and its been 30 or 31 days since i ended i know im not pregnant i just want to know if anyone may know why its not regular like always