Hello, xin chao
I understand what youre going through. Trust me, youre not alone in this. Many of those people who seem happy and busy with their social groups may just be as lonely as you are. And speaking from experience, I doubt being isolated will really benefit your uni results. It actually would work - no distraction, just a goal and to be in your element to push forward - its true, but from how you described your self, i get the feeling that even though youre shy, youre not antisocial, and you do like/need human interaction, just the right kind. You allow your self to be isolated for too long, your mental health may be affected, and that will affect your study too.
So why don't go look for connection? Part time work with/at animal cares or actually do get one if you like animals and your place allow them. Bring your weekend activities outdoor (cafe,libraries, galleries, parks) - fresh air and that