Does Primolut N And Letroze 2.5 Help With The Irregular Periods?

Hi doctor,i want to get pregnant and my periods are irregular hence cant know my ovulation time,i was prescribed Primolute N for 21 days,n at the same time i was given Letroze 2.5mg,is this correct coz i dont understand the work for Primolute N coz i get different answers,will i get pregnant with this combination