birth control pill

i`m taking birth control pill "harmonet" at first i started to take it because my piriet was very painful, but now i keep taking it to prevent me from geting pregnent, the problem is that my piriet comes in 2 days late every time, is that somthing siries that needs to be chek? can that have anything to do whith me starting to have sex? because it was on time before i started to have sex but few months after i started to have sex my pirioed is late in 2 days (i`m taking my pill regilarli, i dont forget and i take same time every night)is this going to damade my fritility thank you for you`re help you may answer in hebrow, a`ll anderstand ,my computer don1t write in hebrow so i wrote in english.

the problem is that even when i finish a package of 21 pills , i dont get my piried right away but only after 2 days.( i take the pill on time and never miss to take any) it happens every month (every month my piried is late in 2 days with no evident risen).i is that normal? does it indicate on a problem and can it be a seriese problem