>>1 The best way to get new friends is to turn your centers of interest into group activities. In this way you can meet people with whom you instantly have something pleasant to talk about, and fun activities to share. You like videogames, manga and anime: I suggest you look for conventions about those in your area, search your university about clubs sharing your interests, find the local shops where people with the same interests as you can meet. You could event think about initiating some activities by leaving a message in the local university boards (physical or electronic).

If you enjoy manga, you could think about making an amateur work, and you could talk with people in the local arts classes, for instance. Really, there are tons of way of meeting like minded people in an university.

As for your lack of enthusiasm, this is probably the consequence of a depressive state. Lack of motivation is one of the hallmarks of depression. Do something positive about your relational problems, enjoy yourself, and when it's time to work, work hard and the best you can.