birth control

i take birth control pills ,and at first every thing was normal and my piried came on time,but now it always coms 2 days later(i finish a month package and i take it every day on the same time) but my piriet is late in 2 days for more than 6 monthas now. my qustion is: is that mean i have a problem ? is the problem serious? is there somthing i can do at first i started to take it because of seriuse pain during my piriet, but now iuse it as abirth control since im having sex.can the problem be because of that? because it started to be late after i started to have sex, but i can`t be pregnent since i take the pill regilarly, right?!s thank you you can answer me in hebrow,my computer don`t write in hebrow

i take birth control pills, on regilar basis without missing any,and every time i take them and complite the 21 tablets,my piried doesn't come as it sopose to ,it comes only 2 days later (every month) is that somthing normal? should i worry about it? can it be serius thank you