Two failed IVF with healthy embryos

Hi! I recently had 3 failed iuis and two failed transfers with seemly healthy embryos (BA BB) These eggs were from when I froze them at age 34. I am now 40 and have no embryos left. I have had a normal hysteroscopy, good lining etc. After we lost our only two embryos we tested my partners sperm and his DNA fragmentation was 47% (history of hard hitting reproductive toxic chemo over 12 years ago). On top of that, my AMH has decreased from 1.8 in Feb to .6 this month. My AFC was last checked around a year ago and I had 11, now I have 6. The general consensus is the reason these failed must be related to egg/embryo health and not related to my partners sperm. I responded well to high dose meds my first round 5 years ago. I ended up freezing 15 eggs. From that, 3 embryos were formed and two were euploid. We were told our chances were high with these two embryos, so it’s been pretty heartbreaking. Especially given my age now and decreased numbers.what do you think went wrong and how should we proceed? With the likelihood of needing a couple egg freezing cycles (low AFC) is there value in freezing at day 3 or perhaps transferring fresh on 3 or 5 depending on how they look? I started DHE a month ago and likely clomid and HGH with this next cycle. We will be using the zymot chip with this next cycle. Thoughts? Would love your help as I feel pretty hopeless and scared. Thank you.