Update: Finally made it to transfer

Ta
Transferred our sole embryo this morning. Opted to do fresh Day 3 without PGS as everything went kaput by Day 5 last cycle. Today's eggy was a 6 cell grade 2 (grade 1 being best) but with some multinucleation. I'm trying to stay cautiously hopeful for my husband's sake, but in my head, I'm thinking that it's not going to work. 
This was IVF#2 for us. We have unexplained infertility though my AMH is low. TTC#1 since August 2014. We've been able to conceive naturally without a problem (first time each time), but each time resulted in a MC (3 in a row). After the last one, we moved onto IVF.
And here I am now, hoping that this eggy makes it but trying not to set myself up for more disappointment. How do you balance optimism and rational self-protection?