Thanks for the query.
Emergency pill can alter the menstrual cycles depending the period of menstrual cycle when you took the pill.
For more details:http://srsree.blogspot.in/2012/08/emergency-contraceptive-pill-short-term.html
If you have taken the pill in the second half of your cycle it can postpone your periods.
Your symptoms may also be because of these pills.
So you wait for one more week possibly by tha time you will get periods, if not once go for pregnancy