Renatjie, you do know that there are only about 6 days in your cycle that you can get pregnant? Even during these 6 days the chances are only good on about 3 days. Even on those days doing everything right, only 1 in 4 couples will get regnant each month. After a full year only about 85% will be pregnant.
The normal single dose pill is not effective taken after sex. Only the normal dose of 1 a day at the same time can almost guarantee it (3 in 1000 woman taking it correctly will still end up pregnant).
Even the morning after pill and doubled up doses of the normal pill after sex are less than 75% effective (meaning that 1 in 4 woman taking the morning after pill still stand a chance of getting pregnant because the morning after pill did not stop ovulation or the uterus from preparing for implantation or thickening the cervical mucus to prevent sperm from entering)
Don't be fooled into thinking because you did not get pregnant your routine is working. If you are old enough to have sex, you are old enough to take the responsibility for using birth control correctly and have safe sex if you do not want to have a baby.