What would cause a person to go against their own nature?

I'm gonna try to explain this simply, lol. I'm basically trying to understand what's been going on in my life.

As a kid, I was your average kid - bubbly, sensitive, adventurous.
As a teenager, I was in a school environment where I was uncomfortable. I became withdrawn, unnaturally quiet/silent at school, depressed, anxious.
In college (never received proper counseling for my high school days), I was aloof and almost compulsively perfectionistic.

I'm 24 now. I'm happy to report that, through A LOT of soul-searching and counseling sessions, I have managed to finally reach that person who was underneath all that pain.

I'm no longer withdrawn, quiet/silent, depressed or aloof. I've shed most of my perfectionism and I take something for anxiety.

I look back at those really bad stages in my life (because I'm still reminded of them) and I realize that I was going against my nature many times. I wanted more friends, but I ignored a lot of people. I wanted to be spontaneous, but I stuck my nose in a book. Can you see how that would've made for a miserable existence? I was doing the opposite of what I really wanted.

Do you think that was due to depression, anxiety, hormones and just trying to find ways to cope with being in a school with high expectations?

It's still an awkward transition. Some days I feel so conflicted because I was coping badly for YEARS. Now that I'm somewhat healthier, it's like I'm finally feeling like myself again after so long--but I still have memories that are like zingers to my spirit sometimes. So, I have some moments when I feel off or out of it.

Idk sometimes I wonder if I'm dealing with some form of PTSD, though I'm careful with that because there wasn't some serious physical trauma. It was more like a series of events that seriously disrupted the flow of my life and my sense of self/personhood.