Hello and welcome to ‘Ask A Doctor’ service.  
I have reviewed your query and here is my advice. 
I pill was taken in within 1 hour to prevent the 
pregnancy. Only one tablet is sufficient to prevent the pregnancy. It is very effective in preventing the pregnancy (95-98% success rate). So there may be 0-5% chance of pregnancy if you have done sex in the fertile phase of the period. Another I pill was taken after 12 hours. Second pill is not advisable as it cause 
hormone imbalance. It causes earlier period, delay in period by 1 to 3 weeks, and excessive bleeding can occur. Now your period could be due to 
hormonal imbalance or pregnancy. I would suggest to go for urine pregnancy test and or blood HCG after consulting the gynecologist to confirm pregnancy.
If pregnancy test comes positive then still intrauterine pregnancy will be terminated by 
abortion pill under the advise of a gynecologist. Avoid 
stress, take healthy diet, drink plenty of water and do regular exercises.
Hope I have answered your query. Let me know if I can assist you further.
Regards, 
Dr. Sagar