My experience says test and let your DD decide.
My oldest (freshman) needs to go up to a 33 to get better outside plate coverage. She had the drop 11,10,9 easton ghost and chose the drop 9 because it felt the most balanced to her. she used it mid-season of high school varsity and put one off the center field fence her first at bat. Third at bat she swung and missed at a pitch (her first swing and miss in over 12 games) bat went back in the bag and went back to her 32/22.
Unfortunately girls can be very fickle and change on a dime. I have learned you can try to convince them what is best for them but the experience is what makes their decisions.
Hopefully I can get her to pull back out the 33/24 and accept it and move forward with it but at this point I have to let her do it on her own.
When my DD transitioned from a 32 to a 33, she had some moments of struggle, and some periods where she used only the 32 in games. For some reason, the 32-33 transition was slower for her than any of the previous ones. It's been over a year now. I'm hoping she grows a bit more (currently 5'-6", 150 lbs), but we shall see. She might be using a 33 for the rest of her playing time.
A good friend of my DD (same age, same height, bigger, strong kid) is using a CF8 32/21. Every time I see her with it, it screams "too small" to me. She mashes HRs on a regular basis with that little thing. She doesn't want to give it up.