This is adorable! I would have loved to have that kind of relationship with my dad, what a blessing...in awkward disguise, lol.
A lady in Nordstrom gave me the best bra-fitting ever, along with the best bra ever. Not sure if it was the Nordstrom training or just that particular woman, but could be worth a shot. It was also quite hands on, but she was too matter of fact for me to feel weird about it. She just looked at me blankly like yeah, this is what's happening...duh!
Sounds like your daughter could have been told the wrong size, but for future changes in sizes..bra or otherwise, tell her that dressing for your size makes you look and feel so much better than when you try to squeeze into something smaller anyway! I've been there before with pant sizes and bra sizes, and once I got over the fixation on being a certain size and just went with it, I actually looked smaller! Go figure