What Causes Late Periods After Using Delay Period Pills Previously?

hi dis is sakshi i took 3 tabs of sysron n five mg to postpone my period last month bt it doesnt happen i got my periods after taking the tab so i stopped taking it. bt in present month i hvnt got my periods yet my periods are always on time and dis time it is delay by 10 days till nw. as i m nt involved in ny relnship so no chnaces of pregnancy. so wat could b reason behind dis. from last few 2 to 3 mnths i was having period on time bt was vry sht duartion it finishes jst in 2 days. plz telll me wat it could be.