PGCC Help Please? :3

[PineappleWine]

Hello fellow bird lovers! I have a few concerns for my 8 1/2 year old Pineapple Green Cheek, Baby. I got her about a month ago, and the lady took EXCELLENT care of her. She was on a good diet, mostly pellets and some seeds with a few fruits and veggies every day. At the ladys house, she gave me time to spend with her. Baby was very sweet, and let me pet her, and would step up without hesitation. She had a sister but they had to be separated because someone else was buying the other one.
Once we got home, we left her alone for the day, except the occasional step up so I could re arrange the cage and toys to how I liked it. She was so cute, and from day one loved to go on my shoulders. She would preen my hair and nibble lightly on my lips. She ate the food that I put in the cage (ZooPreem pellets, seed mix, and the occasional treat. She didn't really eat her fruits or veggies I noticed)
We took her to Exotic Birds, to get her one more toy, and to get her nails and wings clipped (although he said they were already short from the lady when she had them trimmed) The man said she was in wonderful health, and was very healthy considering she came from another owner and just came to my house.
But after that, she started to act weird. I recently noticed she switched to only eating the seeds, and no pellets. She bit just two of her tail feathers. They are now shorter and rugged, but not horribly. She now hates my hand, despite constantly trying positive reinforcement. She still loves my shoulder and a few times hopped onto my shoulder when I was laying on my bed watching parrot videos (she loves to watch them:3)
I'm very concerned for her health and I would dearly appreciate anyone who could give me tips! Thank you so much!
Love~ PineappleWine & Baby

[Wolf]

Let's just begin with the fact that there have been a lot of changes in a short time for your bird, which have had her stressed out, parrots do not respond to change very well. Please don't take anything that I have to say as getting on you, because that is not how I mean them to be. With the information that you gave me to work with it is quicker and easier to point out things that you will want to look at closer and change than it is to pick out things that you are doing right. I can see that any mistakes were in an effort to do well by your bird, but that is how most of us made our first mistakes too.
You brought your new friend home and left her alone for most of the day. I am doubting that you actually left her alone as much as you thought you did and that is probably a good thing. I say this because you were tinkering in her cage to get it all set up. She did in fact need you to be close by and talking to her to help relieve the stress of a new environment and new humans. The only mistake was being in her cage this early, with her in it as this probably caused as much stress as your presence relieved.
Despite anything that the person at the pet store may have said your bird was probably in better health than anything in his store, but by taking your bird there it was exposed to some possibly very nasty bacteria and is the reason that all new birds after the first one needs to go through a quarantine period before they are allowed near your bird. If you provide your bird with natural wood perches from bird safe woods with the bark left on them you should never nee to trim her nails. As for clipping wings, I know that you were probably told that it would make her more manageable and that it was also to make it safer for her. This is wrong on both counts and does much more harm than good for your bird as it was designed to fly and all of its bodily systems are directly tied to this ability. I could never find the logic in trying to make your bird safe for the environment by removing or impairing its best means of escape from danger, I always thought it was easier and worked much better to make the environment safe for the bird to live in.
You are going to need to do some research on your birds diet and nutritional needs. I just finished looking at Zupreem's product sheets for a wide range of their foods and two of the first five ingredients are soy and sugar. Many birds have an allergic reaction to soy and soy products and they can't process complex sugars so it contributes to causing diabetes in birds. Most birds free fed seeds and pellets will in short order usually quit eating the pellets, this is normal, but it tells me that in addition to needing to understand diet and nutrition you are going to need to look at how you are feeding your bird.
Some of the changes that you have noticed are simply due to the bird becoming more accustomed to her new environment and so this is reflected in her behaviors. This is the best that I can do with the information that you have given me to work with, The way that you have done things including the mistakes show me that you care about your bird a great deal and that you really want what is best for her. If I am going to give specific advice on your bird then I need additional information. Birds are very intelligent and complex creatures and they teach us as much or more than we teach them. So what I need is a more detailed picture of what is happening in her life. To this end tell me about an average day in the life of your bird starting with the time she gets up, when and what she is offered to eat, what she does all day long, how much time she spends out of her cage, how much of that time is spent with and on you, when she goes to bed and if her cage is covered or not. Cage size would also be helpful.

[PineappleWine]

Thank you for your reply, it was very helpful! Ok, now ill try to be as specific as I can here :3

-Wake up at about seven each day, let her out and talk to her until about nine or ten.
-sometimes I have summer classes to do, and when I get back, I let her out from about one to ten at night, I usually play most with her after I get home.
-The lady had her food in the bowls, so I left them alone, afraid she wont eat any if I moved it around. So she can free eat all day, I often watch her eating and that's why I noticed her only eating seeds. there are two bowls, one for pellets and fruits one for seeds. (I feel so bad, I should have known this wasn't good for her)
-usually for a few hours in the afternoon I take her perch of from the top of the cage and put it on a table near my bed and just lay and watch videos. sometimes she will hop off and onto my shoulder.
-the cage is what the lady had for them when we went, its about 2 ft 4 in tall Cage part, its a stand up one, 2 ft wide, with about 1 ft 5 for width. I have two chewing toys, a millet thing to let her forage more, and a sand perch (she doesn't like to go on it, so that's why we need her nails trimmed) we also have a ring for her to stand on, a tent for her, and one more bell toy.
-she goes to bed with a blanket on her cage, its not big enough to fully cover it so she doesn't suffocate
-most of the day she sits on her perch, or climbs around her cage.

(if you need anything else, tell me, I have to go to a class now and I don't want to be late! Thank you so much for your help!)
Love~ PineappleWine & Baby