What testing should I do for failed implantation??

I’ve had two failed fets. None implanted... I’ve transferred 3 total. they are day 3’s, but I was told because of my age, at least 60% of my embryos should be normal so they didn’t recommend pgs testing. My husband and I are both 26 with unexplained infertility of 4 years. I’m getting an ERA next month, but I was wondering if there are any blood tests I should do. I did Intralipids last time and hcg wash and embryo glue but my embryos still didn’t stick... I have 4 embryos left. I had a laparoscopy two years ago and nothing was found...