@Golden Egg That's fantastic Luv!! Nothing wrong with an early blastocyst at all. Your embie is doing exactly what it should be for Day 5
There are many factors that influence why embryo's may not be as advanced as we'd like them to be on transfer day. One of them is how old the embryo actually is which if you had your eggs ICSI'd would depend on what time that was done and the egg fertilised for eg.
I say Yippee!! for being PUPO Luv!! for a BFP and that your other embies make it to the freezer too!! Are you on any P4 support?? Keep us updated on your progress