Hi, My wife got periods on 28 dec 2018, but
Thanks for posting the query
Kindly wait for 1 more week and repeat the test again.
Do get Beta HCG test and USG abdomen and pelvis to confirm once.
If it is negative even after 1 week, then she can take tab. Deviry 10mg once a day for 5 days and stop.
Then she'll get the cycles with in a week of stopping the tablet.
Cause of delayed cycles can be many.
Once in a while can be ignored
If it repeats then causes like thyroid and PCOD should be ruled out by getting the investigations done.
Any issues do follow up.