UNEXPLAINED INFERTILITY POST BLIGHTED OVUM

I’ve been experiencing unexplained infertility post blighted ovum which happened July 2020. I’m 32 + now and seeing RE and on letrozole cycle#2. I’ve done all tests like baseline US, AMH, FSH etc The only issue I had was thyroid which is now okay since 4 cycles. Husband has perfect sperm. But nothing found and nothing happening?

Anyone here who can coorelate? I want to know what worked for you ? I’m desperate being 32-33 and want to try what will work. Is it okay doing letrzole with trigger shots or directly IUI ? Which has highest chance ?