What Causes Delays In Menstruation?

my mirena was removed oct 28 2010 during my menses trying to conceive i had it for three in a half years i had regular periods november and december i had sex during my fertile time january 5 thru 9 and i ovulated on the ninth i had sex how many cycles its gonna take before i get pregnant my last period was dec 26 for five days i think the next one should be jan 23 according to a online menustration calculator