Frozen Embies!

Sarah • 3 pregnancy loses. 4 failed IUIs, IVF with 1 failed frozen transfer and finally have our healthy boy!! Momma of a 3 year old, angel twins 10/19, and successful fresh IVF is giving us boy two in November!
I just got the call that 9 embryos made it to freeze. 1 from day 5. 4 from day 6 and 4 from day 7. I have no idea what difference it makes based on the day. Anyone have any idea?! I cannot wait for my transfer!!