Birds will feather pluck for multiple and or different reasons, from stress, illness, boredom, malnutrition, and loneliness, or a mix!
I'd definitely take her to see if she could be sick, and make sure that while you're there you talk with your avian vet about other possible reason she could be feather plucking (like if what you feed her is the right kind of food, do you have enough/the right kind of toys, etc).
There are some cases though, that parrots will feather pluck regardless of how happy or healthy they are. But as long as you thoroughly discuss everything with your vet you should be alright! Good luck!