Years ago I read something in a magazine that I’ve recalled when anxiety is rising: everyone has holes in their socks.
Your mom is right. As long as you are alive, and having interactions with others, there is the opportunity for you to make friends. If you are interested in something, join a club where you are already among people who like, and do, what you like and do.
Don’t look away or look down as you’re passing people in the halls, and, if things get lonely and start to feel helpless, take a deep breath and do something audacious: pretend to need a study partner, or to copy class notes, and casually ask the person you think is the nicest or funniest, if they can help you out. That at least gets you into a place where you will have to have a second point of contact with this person. Who knows, it could become a reciprocal thing, and that could lead somewhere.