Hi thanks for your question.
Relax and don't be tense,tension is the one of common causes of delayed periods.
There are negligible chances of your getting pregnant from this sexual act for followig reasons
No 1.This sexual act took place during safe period.
No 2.You were on contraceptive
No 3.You took emergency contraceptive pills with in 72 hours.
The cramps your having could be due to morning after pill.
Delayed periods could be eigther due to tension or morning after pill has disturbed the patteren of your cycle.
Hope I answered the question