If you are experiencing irregular periods or a delay in menstruation, it is important to take care of both your spiritual and physical health. For your physical health, you should consult a doctor to identify any underlying medical issues, such as hormonal imbalances, stress, etc. Along with medical care, you may recite the following Wazifa:

وَيَسۡـَٔلُونَكَ عَنِ ٱلۡمَحِيضِۖ

Wa Yas’aloonaka ‘Anil Maheedi

Recite this openly without any specific count, until your periods start. Also, do not forget to maintain a healthy lifestyle.