PCOS with anovulatory infertility — ovulation induction: letrozole vs clomiphene vs gonadotropins

A 28-year-old woman with PCOS (Rotterdam criteria) has been trying to conceive for 18 months. She has oligomenorrhea, AMH of 8 ng/mL, and BMI of 28. What is the first-line ovulation induction agent — letrozole or clomiphene — based on current evidence (PCOSMIC trial)? When should we add metformin? At what point do we escalate to gonadotropins or refer for IVF? How do we minimize OHSS risk?