Hello dear
I understand your concern
You have did sex in the fertile phase of the period.
As you have regular cycle of 27-28 days, ovulation occur at 13th or 14th day of cycle.
You took Next step pill with in 72 hours but after 24 hours.
It has effectiveness of 80-85% in preventing the pregnancy
So there may be some chance to become pregnant.
Pill can cause earlier period , delayed in period by 1-2 week and excessive bleeding in period.
Wait for the period to come. If period will delay by more than 2 week then go for urine pregnancy test and or Blood
HCG to confirm the pregnancy
If you will be pregnant then you can still terminate intrauterine pregnancy by
abortion pill under the advise of gynecologist
Meanwhile avoid
stress, take healthy diet, drink plenty of water and do regular exercise
Hope this may help you
Contact further if follow up needed
Best regards
Dr. Sagar