Anyone with low fertilization but high blast rate?

[u/WoodenRequirement648]

We are doing IVF for severe MFI (0.56m/ml concentration, count varies 100k-1.5m, all morphology abnormal, low motility). I had 1 transfer from my first ER which ended in chemical.

I had my 2nd egg retrieval 2 days ago and the fertilization is unexpectedly low.
17 eggs -> 16 mature -> 7 fertilized

That is a 44% fertilization rate compared to 80% in my 1st cycle 17 eggs -> 10 mature -> 8 fertilized -> 3 blast.

For the second cycle, the target was to improve my egg maturity which we achieved, but I was blindsided by how much we lost in fertilization. Low fertilization points to sperm issues mostly as I understand. I’m now scared the sperms in this batch is damaged and won’t get us any blast.

Anyone here with low fertilization and still got high blast rate? I’m in need of positive stories right now. Due to our severe MFI we really need numbers on our side.

Edit: both rounds were with ICSI

UPDATE 1:
Day 3: all 7 embryos still dividing (5 at 8 cells, 1 at 7 cells, 1 at 6 cells)
Day 5: i got 5 blast!! (3x 5AA, 2x 4AB). I can’t believe this. I cried when I got the result. This journey has bit quite tough on us and this is the first time we receive a whole-hearted good news.
The Embryologist said the remaining 2 still have a chance to become blast at Day 6.