thanks for your query.
Your next period should come on time but it may be a few days early or a few days late.
However, in case your period is delayed by more than a week, please go in for a pregnancy
test and contact your doctor.
and headache are some common side effects after taking i-pill. You might also have some lower abdominal pain
or find your breasts more tender than usual. All this should stop within a day or two. There are chances of unexpected vaginal bleeding, but this is not dangerous and should clear up by the time you have your next period.
So i recommend you to wait 1 more week and then get UPT done.