What Causes Delayed And Irregular Periods?

Hello Doc Myself Akanksha and i m 25 years old a married girl. I got married in may 2013. From last December i am not getting my mensuration cycle on a proper interval I mean the days are increasing almost by 8-10 days. In nov it was 22 nov then from dec it went to 31 and in feb again 8th and now in march yet not arrived and its almost 16th today. Is it ok the increment of such a long gap.