Point

I'm in an identity crisis. I don't know what I should do. I have too many interests and I can't find out which one fits me the most.

I used to be good (above average) back in my school days. I was good on almost every subject in school. Got pretty high rank in my class. I was happy and I was glad. But I was wrong. I realized I was a generalist. I put so many interests in so many things.

And now? Oh you don't want to feel what I'm feeling now.
Every day I think and try to find out my main major interest but up until now I still can't find it.
It's too hard to find when you're a generalist. I can only eliminate little things that I don't want to do. But eliminating them still left me many lists that I may do, meaning that I still do take interest in them and I still need to look up whether they really fit me.

So, if you are not doing good in your school days, be grateful. That means you know better what you dislike from your younger self.  You eliminate things better. You know your direction.