I have no friends

Like seriously I have no friends. Im super shy and awkward around people and never know what to say. This dude has been snapping me and he'll like say something like 'life sucks kms' or 'I'm soo bored' and I'll end up saying nothing and not replying becaus of my weird social awkwardness. The only person I really talk to is my brothers girlfriend but still then I don't know what to say or do. Like what so I do with my hands or how do I stand or what do I even say without sounding rude or disrespectful and making them think I don't want to talk to them. I sit with two random girls at lunch and don't even know the ones name. I don't know why I am like this but I'm always beating myself up about this and I think like ok you can do this just go say hi it's not hard but I can't bring myself to do it. At home I'm probly the most crazy person out there but then wish I was like invisible when I step out of my house. I'm not even like self conscious about my looks or body I'm just not good around people. I do feel like I'd be a little clingy though and want my friend all to myself, probly because I've never had someone I could just say anything to but don't just want to talk about myself. I not very good at giving advice. I had this one friend once who was upset and I did not do a good job on trying to make her feel better and then I'll just stand there all quiet and weird. Every time someone will try talking to me I'll get all red in the face and like nervous sweat and stutter and get all flustered.