HELP!! Why do I feel the old me is a better person, a better human-being?

I am turning 23 this year, just graduated from master, unlike some similar questions, I don't feel old at this age. All I'm feeling is, who I was a couple years ago were better than who I am now.

When I was younger, about 14-18, I used to be like a fairly hardworking person, I didn't complain't if there were too many works from school, I finished them on time, I studied all days every week for exams, I went to basketball training regularly every Saturday and Sunday for 3 hours. I hated the feeling of losing in a game, I was always looking to win. I was confidence at what Im good at, I was a confident person in general.

But things changed ever-since I started uni, I feel like my confidence is going away, I am no longer motivated in sport, it feels like it doesn't matter even though we lose, that kind of feeling that you want something so badly (eg winning) has gone. Im being less out-going, less sociable, I don't feel like talking with strangers, or people Im not closed with, not because Im not comfortable, I just dont want to, dont feel like to.

I dont what has happened during uni. I don't start working in the last minute, my grades were bad (graduated with 2:2, undergrad). I feel like there is noting to keep me going. I m not sure, I want the old me back, it is like that, myself a few years ago was the one I wanna be. I'd like to care about winning and losing, I'd like to care about things, I'd like to be motivated, to find sth that keeps me going, WHAT HAPPENDED?