Well I'm sure if you hang out with the one friend you made, they will introduce you to their other friends and you may get on well.
I would also suggest going to your course socials, maybe bring that friend you have or go on your own.
If you have group work this year, put in a little bit more effort to talk to at least one of them. Maybe say there's this event you want to go to and see if they're up for it.
Sounds weird but tinder can kind of work. You can get chatting and decide to meet more casually and remain friends. Meet their friends as well. Or you could date someone for a bit and then make friends with their friends. Obviously don't date them for that reason.
Are you in second year right now and approaching the end? Or first year going into 2nd year in september?
At the start of next term you can always join a society, even if it seems a bit lame, you're bound to meet some people.
If you're really struggling then I would suggest getting a part time job, either retail or bar work. Everyone I've met who has had a part time job at uni (particularly bar work) has made a decent group of new friends.