Can't make any friends and getting tired of it

So I have always had a hard time making friends. Right now I have one good friend that I have had since 8th grade (I'm 21 now). I have been working full time for about 2 years now and I have made no new friends outside of work so my social life consists of myself and my one friend and even when I try making new connections nothing works. That friend also always claims that she has no friends and struggles to make friends but I have a hard time empathizing for her when she makes new friends all the time. We were working at the same job. Within a month after we started working there she had made 3 good friends and was hanging out with them outside of work already. I felt like I was super good friends with them too at work but never met them outside of work like she did (she was meeting them seperatly not all together). We did all go to see a movie last summer together but only because it was my friend that planned it. One of them invited my friend out to dinner a couple of weeks ago (we recently quit and she missed her and wanted to catch up) and she told me that she also used to sometimes meet one of them on weekends soon after she started working there. I was added to a group chat with them last summer but the only reason I was added was because my friend added me. I talk to them there but noone talks to me outside the groupchat like they talk to my friend (seperate converations about personal stuff).

But today one of them randomly messaged in the group chat "are we still on for lunch at 15?" when talk of lunch had never come up in the chat before. We say all the time thing like "omg we have to meet for dinner soon or something we haven't seen eachother in so long!" but never do anything about it so this was really random. It's like they had talked about it on a seperate chat but accidentally sent it to this one which makes me feel like they wanted to meet up but not invite me. I also saw the other day a notification on her phone that she got a snapchat from a girl that literally started working at the job 2 weeks before we left and apparently they talk all the time now. We also bump into people she knows ALL THE TIME but still she constantly complains to me how she is so awkward and has no friends and noone wants to be her friend when people ask her for her socials within the first time meeting her and start talking right away. She rarely takes initiative it's other people asking her and she has so many friends. She meets up with people all the time but constantly complains to me how dry her social life is. To me... who she knows has literally one friend which is her. Like, I know she is saying it because she feels like she can trust me and talk to me about her struggles but I can't help but feel like it's a little selfish or something, it gives me the same vibes as when a skinny friends complains about how fat she is to her overweight friend (it's happened to me before so).

I feel like I'm being as friendly and nice and interesting as I can to people I meet but there is never any interest in meeting me or talking to me outside of the situation we are in when we meet (for example work friends hanging out outside of work) and I am seeing all of these people becoming good friends right in front of me. Am I that unapproachable? What the hell am I doing wrong? Do I give off a vibe saying don't talk to me? I am trying so damn hard I even took initiative and sent a message to a person that I felt like a made a friendly connection with the other day but the chat was one-sided, short and awkward (on there side) and I really don't know what to do at this point. I am just so freaking lonely and my struggles are turning into resentment toward my friend which is not fair and I hate is happening because I know she means well I really do! please help...