My husband (35) and I (30) have been trying to get pregnant for almost 2 years. His semen analysis is normal. I have mild PCO but very regular cycles. My tubes are patent. I'm on my third round of letroz. Post this cycle, we will consider IUI/IVF. But we're wondering what is going wrong. Both our prolactin was elevated slightly but was corrected. Both of us are on metformin. I'm on metformin with myoinoditol. My BMI is 27 and his BMI is 29. Our TSH was below 3 till 2 months ago and suddenly both of us are at 5. We're taking thyroxine 25mg every morning. Vit D was low and was corrected. Otherwise, all hormone levels are normal. My AMH is 2.8. We have not gotten pregnant even once. No chemical pregnancy, no miscarriages . What is causing this infertility?