Hi there, I have understood your concern and I will suggest you the best possible treatment options.
First of all do not panic.
As you might be aware that in a woman with regular cycle day 10 to 20 of the cycle is the most fertile period of the cycle.
If you happen to have unprotected sex activity in this period then only there is chance to get pregnant.
As per your history, your sex activity was not in the fertile period.
So chances of getting pregnant are almost nil.
Also, negative
pregnancy test rules out pregnancy.
I will suggest that she should seek prescription support from treating doctor for Tablet
Regestrone 5 mg twice a day for 5 days. This will induce periods in 3 to 10 days after finishing the tablets.
Please seek proper sex counseling services for safe and protected sex activity.
This will help to prevent unwanted pregnancy and STDs.
I hope this answer helps you.
Thanks.
Dr. Purushottam Neurgaonkar