Hello mate.
I’ve no idea what you’re like as a person in general. But, by making this post it’s clear you’re willing to take steps to change some things for yourself which is great. As people have said above, join a society. This will give you a social experience and they frequently have things that require interaction. Through this interaction you’ll meet people and may even meet some first years who have also joined the society to make friends. If your uni also has a volunteering community, join it if you’d like. The people volunteering aren’t usually the worst types of humans and in my experience are a friendly bunch. I came to uni as a mature student and I was really worried about spending a lot of time on my own and at the start, I did. But I started making changes and gained a good group. One of the things I did, was talk to people about the course, the classes, the work. We organised study groups and that turned into hanging out away from study and uni too. Hope things get better for you and reach out to the unis student welfare or your own doctor if you feel your mental health is in a bad place.