What Causes Delayed Period After Taking Emergency Contraceptive Pill?

i took an emergency contraceptive pill, i dont even remember da name. but i knew that i have to take 2 of them, instead i took 4 in da mid of november. on about 10th december i had periods but i'm missing my 2nd periodx. n0 symptomx of them yet. could i be pregnant or thr could be some other reason behind this delay. plz answer me i'm too worried.