Help on Feterilty treatment

Hello-

I took a break for almost 9 months since my last treatment failed. Im back and ready to start my 4th treatment and was told I only have 2 tries left after this one and if it doesn’t work then I will need to seek IVF after my 6 attempts. Today I just started my cycle day 1 and will get some blood work done tomorrow, and meet with my RE on Friday via video conference to discuss the next steps and treatment plan. This will be my 4th time using letrozole to induce ovulation since I have dysfunction ovulatory due to PCOS. The first 3 times failed but in between those cycles I got two positive pregnancy test, but lost my baby at 21 weeks and the second was a chemical at 5 weeks. I am asking for some suggestion if anyone can advise me on what I can do differently this time with my treatment to increase my chances of getting pregnant. Last time I was put on 5mg letrozole and responded with two mature follicles measuring 18 and 17 and triggered the ovidrel shot a day after I got the mature egg at 18 but still no successful pregnancy test (also first two cycles was also triggered at a 18 follicle and failed both times). Per my RE, I will again be put on 5mg for this cycle. Currently taking prenatal and CoQ10. What should I ask my RE to give me, should wait for a more mature egg at 20-22 before triggering and what other tests should I ask the RE to run on me? TIA.