Less and less blasts each cyle

40.9 years old, done 4 cycles with a decent egg number and 3 euploids banked with sperm donor.

It was already a difficult decision to do this on my own to become a single mother, I was hopeful when I got good number of eggs and 3 euploids but now it seems like I ran out of euploids.

I switched donors after banking the euploids but now I can’t get more euploids. I was hoping to bank another 3/6 euploids before starting FET but I have less than half number/rate of blasts, zero euploids.

Will I have euploids again? I know there is cycle to cycle variation, also every person is different. Some get no euploids, some get above average. I wonder if letting follicles grow too big until trigger caused lower blasts and euploids to disappear. Cycles where I got euploids, triggered before any follicle was 17mm. The cycles without any euploids, triggered after half of follicles were above 20mm, some even at 25mm. Doctor refuses to change the protocol or doses.

I am tired, devastated. Should I change clinics and lose 2/3 months time or continue with the same clinic and risk having another low blast and no euploid cycle?