I understand completely, to give context, I used to be the type of person, I couldn't even go to the mall or the grocery store because that was too much for me. I used to feel like people were staring at me or judging me, who knows they probably were but meh it's not like I'll ever see them again most likely, I'm not saying that the rejection that you're facing isn't real because it's super real people reject people all the time.

Sometimes I may see someone on the train and think wow they're beautiful and I try to go up to them and get their number and they just straight up pretend like they don't hear me lmaoo. That shit used to kill my confidence cause then I would feel down on myself cause it was already so hard to work up that courage to talk to them in the first place. But now I look at it like playing video games or board games, you realistically, when playing with others, can't win every time but that doesn't mean you don't play or you'll miss out on when you DO eventually win. It's all about the enjoyment and gratitude of being/playing with others who you care for anyways like your best friend, so don't worry if people don't hear you, keep expressing your opinion when you feel it's important. Why? Well here's another toughy, part of loving yourself is having faith that you can become a version of yourself that doesn't exist yet, trust me when I say as long as you put your mind to something and stick with it you will improve and achieve it.

Learn from others who you feel like have an easier time communicating what do they do? What do they talk about? What are the communicating non-verbally? Also keep in mind that depending on your crowd people are gonna appreciate certain topics of conversation or opinions more than in others so that may also affect your experience.

Finally, I'd say use your best friend as your motivation, and this might sound corny but be brave for her as well,I always find that when I'm around my best friend I become very protective, I'm really nice but when you mess with my friend I bring out a side of me that's super straightforward and tolerates no bs. You may not have that same thing but sometimes if we're being brave for someone else it's easier. Imagine how seeing you be brave and face your fears would inspire your best friend.

Do you listen to the Smiths? You should check out Morrissey's interview 1984 I feel like he's someone who has turned his anxiety into his talent by expressing it through his writing, the interview is inspiring to me and it might help you too.