Thanks for writing,
If you have used protection then there is nothing to worry.
Also there is no use worrying now.
You may do a urine pregnancy
test if she misses her periods.
A day or a weeks delay can happen due to reasons like stress
, medication and change of place.
If there were no such factors in her case then you have to rule out pregnancy.
After the test, you may consult a gynecologist for the further management according to your report and choice.