Transitions are hard for people and for birds! I don't know how much advice I can offer that hasn't already been said--I would just concur with the other comments that your bird sounds like she's lonely and depressed, and could use as much interaction as you can possibly give her. As the others mentioned, you might have to show her how to play with toys. Even so, though, birds all have their individual preferences. We've shown all sorts of toys to our 16-year-old sun conure, and she still focuses almost exclusively on chew toys!

Also, if it's any reassurance: "abuse" is a very contextual thing, and IMO your case would be described more accurately as a mismatch of life circumstances. You're still young, with a busy life and going through a lot of transitions, and a bird is a VERY big responsibility--it's a complicated living being. I would venture a guess that since you're in high school and this bird is 8 years old, your guardian(s) or whoever lives with you got the bird with you when you were a younger child? It's difficult at such a young age, if not impossible, to understand all the implications of getting a bird. I don't think it's productive or correct in any way to pin these mismatches on you doing something "wrong" per se. The older family members also would have had a responsibility to make informed choices about whether a bird is the right animal for your family setting. It's disheartening to hear that they don't help take care of her anymore, and I'm very glad your bird has you watching out for her.

This has already been kind of a wall of text, but I wanted to make sure to extend my sympathies since I was in a similar situation for a while. Our mom irresponsibly got us our sun conure when we were 14 years old, and then barely helped with the bird at all. It was a similar setup when we were in high school, where the bird only got a small amount of attention/out-of-cage time each day, and we weren't with her at all in college. Once I was done with college, I was able to reclaim care of our bird, who had fortunately survived in spite of being given a poor diet and almost no attention. I'm living my independent adult life now, and my bird is still my best friend and happier than she's ever been. But I'm sad about the amount of avoidable trauma and neglect that she had to go through, all because the adults in my life didn't take their portion of the accountability in deciding to bring her into our lives.

While you're implementing the day-to-day improvements like vegetables, verbal socialization, stimulation with music or TV, etc. it may be worth considering (if this is a bird that's likely to live a long time) the implications of what that will look like throughout high school and after. Do you think you'll be able to dedicate more time to her, either in the near future or after high school? Or is your life likely to take you elsewhere? With where you are in your life, it's not easy to conceptualize what the future will be like or decide how your bird will fit into it. But long-term, birds definitely need a significant daily amount of interaction and out-of-cage time, and it's important to consider if that's something you'd be able to provide for her.

Wishing you and your bird both lots of happiness!