I would go with the date on the box because that was stamped by the drug company. But I would also show the box and print out to the phyarmcy where you had gotten it. Let them explain it.
Phyarmcies often make mistakes and they should know about them so it can be corrected. And if not corrected, they should be reported as their mistakes can be harmful.
I've experienced:
miscounted pills
Given one inhailer instead of the two that was ordered by the doctor and charged for two.
Given someone elses medication.
I now open the bag to make sure I got what I ordered before leaving the phyarmcy counter...I look for my name, the name of the med. and the expiration date on the box or bottle and count the pills when I get home....none of which takes long to do.
Expiration dates are important as products weaken when they go beyond their dates.
I'm also known to pull store managers out of hiding to remove products from the shelves when the expiration dates are old.
I'm glad to hear your daughter is doing well.