Great advice above! Yes, the photo looks like she is over-preening/barbering to me as well. It's good you have a very appointment coming up, as barbering art plucking can have dietary, medical, or psychological causes. So, it's always good to rule out the medical and, to the extent possible, dietary, before anything else.
The biggest red flag for me would be the seed dinners. Seeds should be treats for ekkies. Nothing more. And unfortunately, sunflower seeds are up there with the worst of the lot. Too much seed in the diet can lead to arteriosclerosis, and an eventual shortening of the lifespan over time.
Here is what I currently feed Maya and Jolly:
I tend to provide between 6 and 8 types of food per feeding (2 meals per day), weighted heavily toward the veggie side as only 1 of the food selections in a given meal is a fruit.
Various sprouts, carrots (very important due to the high content of beta carotene - precursor to Vitamin A), bell peppers (red, yellow, orange and green – also very high in Vitamin A), jalapeno peppers, Jamaican Scotch bonnet peppers, chili peppers, squash (butternut, green and yellow), pumpkin (again, high in Vitamin A), blueberries and pomegranates (both among the most nutritious of fruits), snap peas, broccoli (high in calcium), cactus pears, persimmon, starfruit, bananas, grapes (only for flavor and hydration. Relatively low in nutrition), kale, turnips, radishes, brown rice, quinoa, cucumbers, endives, dandelion (nutritional powerhouse offered at every meal when seasonally available), sweet potato (cooked), red swiss chard, mustard greens, collard greens, kale, cilantro, parsley, watercress, arugula, granny smith apples, papaya (don’t go too heavy on this, as it is a diarrhetic), African horned melon, hominy, oatmeal (sans sugar or flavoring), kiwi, barley, calendula flowers, fennel, chocho beans and garbanzo beans, as well as Volkman's Fancy Soak and Simmer for the majority of their legumes and grains.
For food accents I'll add one or two types of the following as well: star anise, milk thistle, elder berries, rose hips, hibiscus, bee pollen and chamomile flowers.
Twice a month, I'll give some hard-boiled egg (with the crushed shell for calcium). Slightly more frequently during a molt.
For their training treats they get an assortment of unsalted nuts (one to three per bird in a given day, broken into small pieces and fed as rewards during the training sessions). And for their "goodnight treat", up to a teaspoon or two of seeds.
Oh, and on other thing! Make sure to provide adequate toys and foraging activities to keep them mentally stimulated. Boredom can also lead to feather barbering/plucking.