I Wish I Had More True Friends

Ever since I left school early due to mental health concerns, I have had absolutely no contact with others outside of work. So I've been working overtime as much as possible (from 6am til 1am) to try and be around people and try to make friends, but nothing's working no matter how kind and genuine I am. I'm at the point where I wish I was still in inpatient so that I could have friends again. I walk to work, stay there for all that time, then walk back, rinse and repeat. There were other people my age I talked to, but they don't care much for me. No one wants to meet up with me, no matter how available I make myself. They're always "too busy" to hang out, but on their snapchat stories they're out with other friends and I'm sitting in my room alone. What's the point of being here if I'm gonna be doing life alone?