why my daughter can see my messages and photos on her iphone

This is because both of you are using the same Apple ID. I am assuming that your daughter is set up with your Apple ID. Log her out of the current Apple ID and then create a separate one for her. This will stop the data mixups between the two iPhones.

Axel F.

It is because your daughter use the same apple id which you are using, so she is able to see your all the things related to that id