If it's hormonal, like your vet says (which is very possible, because this IS an area of plucking when it's hormones), the best thing you can do is: absolutely NO papers on the bottom or access to any shreddable toys & things, 12 hrs. sleep MINIMUM-some birds who are hormonal actually need 13-14. Put her to bed as soon as the sun goes down for sure. NO high fat foods (ie. nuts, lots of seeds, carb foods like potatos, corn & pasta). No sugary foods (bananas, mangos, apricots & other high sugar fruits). No eggs. No estrogenic foods such as soy, cauliflower, green beans, all legumes). You can google estrogenic veggies online & see which are the highest. Bathe, or spray 1-2x's daily. No petting except on the head ONLY. No shoulder bird, no caves or boxes or hutches to stimulate nesting behaviors. Usually, if you do these things consistently, you will see improvement in around 3 wks. If you see no improvement or it gets worse, the vet can give her an anti-hormone shot (I've personally not ever had to do that, but it can be done). Good luck! This is hormonal season for some birds (I'm going through it too), so it's a thing.