Is intralipid the answer? Please help

My hubby and I have been doing IVF/ICSI for 3 years now - still no success, not even a bleep on the radar - just a big fat nothing. Hubby 37 yrs and low sperm and me now just turned 42 yrs and three tranfers ago also found out I had moderate level of NK Killer cells which I have also been getting Intralipid treatment for the last 3 transfers. We always get great ferts and transfer blast and a morulla usually we end up with 2 good ones out of each cyle. I have had 14 egg collections in this time (it is very safe to say that I am over it). Last cycle I even tried luveris and I have also been doing the Colarado treatment with the Intralipid, I had 14 eggs (not bad for an older girl) and 11 were good size for icsi and all fertilised and then we ended up with a blast and a morulla (just a stage before blast) to transfer, my lining was also over 6mm, so we thought all good, but then we always seem to get a negative result. We are at our wits end and as you can imagine I am in panic mode as I am getting older every year, we really don't know what else we should do next. Would really really appreciate some feedback, advice share similar stories as it is always the hardest thing to make decisions of such importance.

option 1. To continue doing transfers with the intralipid hoping it will work - feeling like we are starting IVF all over again with the new discovery, regaridng NK cells, continue what we have been doing.
option 2. Could it be that our embyos are only strong enough to get to past day 5 and then they are dying meaning we have an issue with the sperm or the egg ? Should we be trying donor sperm or egg donor, our Doctor seems to think we keep tryng with our own bits as our ferts are very good but we can't waste another year as this may be our last. The problem is that all the eggs and sperm look good when transferring but we are not getting any further.
Really want to see if anyone else has or knows of a similar couple that has gone through a similar journey and did they get pregnant and how ?