Next time you can use clomiphene
citrate 100 mg from day 2 of menses for 5 days with estrogen
support and then start her on Inj.FSH 150 IU alternate day ( 3 times).Letrozole
is banned nowadays.
Also start her on recent preparations containing myoinositol for better ovulation. if the size of follicle not increasing then consider surgical option like ovarian drilling.