Hey my clinic is the same, they only freeze them if they get to day 5, i also hav one frozen at day 6 which is a good thing, as it means if they defrost the day 5 embryo and it dosnt make it apparently they get day 6 embryo out and thaw that one and because it has developed a day longer it dosn't need much thawing time so it means my cycle isnt cancelled.

goodluck xx