Hi welcome to the health care magic Plan B emergency pill contain synthetic progesterone that is levonorgestrel As it is Hormonal preparation it can delay period.. But you have taken pill before three months.. (in January) Hence it should be further evaluated to identify cause of delay period... Rule out thyroid, diabetes issues by sugar estimation and serum TSH, t4 estimation Excess stress, obesity, prolonged starvation sometimes associated with delay period Local pelvic examination and USG done to identify ovarian causes... Repeat pregnancy test as well... Take care Hope your concern solved According to cause detected further treatment guidance will be given Consult gynecologist for examination and discuss all these