What to do when my personality has changed?

I feel like I need to share this with somebody to let off my steam and maybe get someone's opinion. So I'll use this forum for this. I want to begin by introducing myself shortly. I'm seventeen. I'm a high school junior. The problem I want to share is the drastic personality and behavior change I've gone through in my high school years. I want to explain this more.

I used to be a different person until I started high school. I was hardworking and strong-willed so whenever I wanted to achieve something I'd usually get it by working hard. Therefore, I was a really good student and my grades were high. I was quite curious and into science and philosophy and I'd read books, articles, and magazines about serious topics, of course, the ones for my age group since I was younger than even 15. I'm not a very smart person but I had this strong will and eagerness that put me in front of others who had more capacity than I have. I was a kinda perfectionist, too but I don't think this perfectionism was toxic since it only caused me to work hard when I wanted to get something.

Comparing myself to the person I was back then, I see that I changed. I can even say that I became the opposite of myself. I'm now lacking the motivation to do or want anything. I have no passion in me towards anything anymore. I do things only when I have to, usually at the last minute, and they don't even end up being good. I lost my reading habit. Also, my grades get down, I'm one of the worst students in my class. I feel so lazy and depressed (even though I feel a bit better nowadays). I can't focus on things either and that makes everything harder since I can't get anything done even if I could be able to gain the motivation to begin. Also, I've never been an overly confident person but I used to have faith in myself when it comes to things I was good at or tried hard to have. Now, I have very low self-esteem and don't believe that I can achieve or do anything.

Just to be not fully pessimistic, I can say that some things changed for good. For example, I used to be quite narrow-minded and couldn't think of anything but my ways to get things done and sometimes couldn't understand why people acted the way they did. Now that I've experienced a very different lifestyle, I can see now that sometimes life pushes people to act a certain way. Realizing this made me understand that everybody's lives and ways of thinking are different. Therefore I'm not as narrow minded as I was or judgemental towards other opinions. I also got a bit more "physical". I now care about the way I look and groom myself. Kinda developed a sense of fashion too. I used to find such concepts uninteresting (though that was normal since I was a kid) . I now do sports, which makes me feel a bit healthier and energetic. Still, the bad characteristics I gained outnumber the good ones.

I questioned why I might have gone through this much of a drastic change, and I guess I can see some reasons. In recent years, I suffered from sexual abuse and eating disorders. I couldn't get any professional help and my parents were kinda judgemental towards me which didn't help either. Only a bunch of friends tried to help me, which didn't work out. I had to go through these things by myself. All these things caused me to lose confidence and belief in myself. I guess puberty plays a part in it, too. I don't want to blame others for my behaviors, the way I am is my problem, and I'm also one of the problems here. In the end, a lot of people, unfortunately, go through such things and some of them stay stronger.

I tried to get stronger and change, too. I tried to be more organized, gain some more self-esteem, take care of myself, begin doing sports, start a new hobby, etc. I read a lot of articles on how to be productive, confident, or heal the wounds of past traumatic events (things I've mentioned) and did everything that was suggested there. Sometimes it got a bit better, sometimes it didn't work at all. But no matter what I did, I just couldn't be or feel any better.

Currently, I feel a bit better. I'm not as depressed as I was a couple of months ago. I've been working out regularly for a while. I'm still not confident but I stopped insulting myself inwardly. I also try to sit and study but my grades are still low. I still can't focus on work.

I just wanted to share this. Thanks if you read it until the end.