Hi welcome to health care magic.... You had taken combined oc pills as a emergency contraception ... Four dose is enough and is effective measures for preventing pregnancy.... Here still your pregnancy is positive ... So either it could be contraceptive failure (chance very less) or conception was already there before taking pills ... It should be taken as soon as possible ... You have taken it after one day so although less but chance from emergency failure can be there For exact dating of gestational age , Ultrasonography investigation needed .... Advise : Nearby Gynecologist consultation... Take care