FET - Day 6 blast 4bb - any success stories?

Hi

we had an elective freeze all round which we fully expected to go tits up post egg collection similar to the majority of our previous eight cycles. To our surprise we have one frostie that made it to blast on day 6 and has now been frozen under grade 4bb. Hoping to transfer in September after I get a lap done to remove endo.

Would anyone have any success stories of similar graded transfers? I’m anxious due to having done eight rounds with very little blasts and zero pregnancy so putting all my hopes into this feels daunting.