If she has had blood work done and health checks out, I'd say that this looks like it is over-preening/plucking (possibly motivated by hormones and anxiety). Pet on the head and neck only, get your parrot 10 hours of sleep on a set schedule for the rest of her life, make sure she has no access to huts/tents/shadowy places (even a box with an open top is shadowy for them-- so are blankets and often couches etc), and avoid egg-shaped toys...Warm squishy foods can also be a trigger.
When was the last time she was at the vet and did they test for yeast/fungal stuff on the skin?
What tests did they run?
How often is she out each day and how is her diet? Sleep etc? How big is her cage? Any routine changes?
When you do go to the vet, I'd ask for blood work, a gram stain, and possible swabs of skin-- xrays are another helpful tool (but they can be stressful for some birds).
If all of that checks out, I'd bank on anxiety--- probably in-part, related to hormonal triggers (based on the sites of the patches)--that having been said-- those same sites can get attention in a bird with illness, so just make sure you rule that out.
Is the skin under the feathers raw or irritated and or bleeding at all /scabbed?
If your bird is suffering internally-- like a kidney infection or something, or due to inflamed organs, they will also sometimes pluck at affected areas, which is why a solid vet visit (more than just a physical exam) is important. PDD can sometimes be caught by an x-ray, which is cheaper than the blood panel in most cases.
Have you noticed any behavior changes or changes to poop? What about straining when pooping?