I think you can wait for some more days for a week or so. Sometimes due to hormonal imbalance it can happen also pregnancy should be ruled out even if sterilization is done
Next Steps
wait for 1 week if no others symptoms like pain n do urine
pregnancy test ...if negative u can take tab meprate 10 mg twice daily for 5 days n u ll get periods 3-4 days after stopping tablets
Health Tips
there is nothing to worry