Suggest Treatment For Irregular Periods

Hi doctor.my regular periods date was 29 of every month.according to that i have planned a trip on 3rd of july 2014.so on 28 and 29 only one drop of bleeding happened. i waited till 30. but on 30 no bleeding happened.my journey date is coming near so i started taking primolut-n 2 tabs a day and continued from 30 june 2014 to 8 july 2014. now my periods started on 17 july 2014. but bleeding is very very less compared to regular periods.before and after taking primolut i had intercourse with my husband. not during primolut period. due to less bleeding can i have any chance of being pregnant?plz answer