Well, how tall is Daisy (measured to the withers) and how much does she weigh?
At a year old, she is probably within an inch or so of her adult height, but she's nowhere near finished growing (as in filling out) yet. It is quite common for them to be very ribby at that age too. Boxers don't mature physically until 2-3 years old (and mentally it's at about age 6 LOL).
IMO it is unlikely that you have anything at all to worry about.
PS: Size isn't always that easy to judge from photos, and there are a lot of boxers out there that are a *lot* bigger than the breed is supposed to be
