You have made your choices at home, stick with them! What could that say now that will change that except that only two made it? Anything more and you'll do one and freeze the rest, right? You are fine! They have made it to blasts, so you said you only want one to cut the risk of multiples. (That is what you had mentioned unless you and Dh changed that.) It is a GREAT PLAN and what my DH and I were planning, too! (But then we only got one, so no choice to worry about!)
You don't have to make an on the spot choice, you already made the choice at home with your DH and friends help and advice, stick with that!
Things are going to go very well, do what you have chosen to do so you don't need to second guess!
I can't wait to hear how it goes!
You are fine, this will go well, breath and go with what comes to you!
HUGS and I wish I was there to hold your hand!
(PS- they also don't tell you, I believe, until right before the transfer so that they have the right info!)