Please help I am so alone and have no frjends

]I don’t know what to do anymore. I used to have lots of different friends and eventually I drifted from them all because I thought I wasn’t good enough or convinced myself they don’t like me because I don’t have the same clothes and makeup as then , when they did like me and I realise that. But it’s too late. School starts soon and I literally have anxiety because idk what bag to get which is so stupid but.
I have been alone all summer and my dad thinks it’s weird I haven’t seen anybody.
I miss not being alone and having fun and laughing. Idk what to do and I can’t see it changing.