I'm too quiet for others apparently

I started university 1 month ago (not my first year basically I'm doing a different course in another city) and I casually found this girl during the first days, because we got lost and found each other. We sticked with each other but I didn't like her that much, yes she was nice but we didn't click that much with our personalities. I had the impression she wasnt herself around me. I was quiet around her, like I tried to make small talk (even tho I hate it) she replied but there wasn't fluidity in the conversation. I always felt so drained around her so after a while I stayed quiet. She stayed quiet too after a few small talk.
Then last week I noticed that she was avoiding me, and she was acting like a different person around others. So I think when she was with me she held back because apparently she doesnt like quiet people. She always tries to be friend with everyone, she seems really nervous when she's by herself or when she doesnt talk.
Yesterday I wanted to stick with her (I'm stupid why did I do that if I dont like her company??) because I remembered it was her birthday, so I thought "I want to say happy bday". She was with a few people and she's really talkative around them, because they are too. She wasnt happy that I sat near her, she never looked at me. Then I noticed that one of her friends asked her "who is that girl" referring to me. Then she leaned on this friend and made a gesture to say "that girl never talks" like I was weird. I felt stabbed in the heart, because I noticed their conversation about me. I felt like a total burden at first, like it was my fault. I'm really sensitive to abandonment so there also this. Thats why I felt really bad at first. Even in high school my classmates always said that I was too quiet and I never had friends.

I feel like if I avoid her I'm being mean but at this point I dont ****in care. I dont want her to limit herself around me, I want people to be themselves, so I'll leave her, I'll withdrawn. But it's always like this, people says that Im too quiet. Why is it a problem?? I like to be quiet and I need to be silent sometimes, I feel drained in large groups. I dont want to be friends with everyone like this girl, I prefer to connect a lot with a few people, and staying with her means staying in her large group of friends. I dont care about their friends because they only small talk.

Today I skipped classes because I had thoughts like "nobody wants you" "everyone hate you" and I avoided going to class. Tomorrow I'll go and I'll sit by myself on my own..I thought this girl was ok with me, yes we didnt talk that much but I didnt notice it was a problem until last week.

It sounds like you're an introverted person. That's not bad, but it does make it hard for people to spend time with you. I was the same way, but I learned how to make small talk and ask people about themselves (being truly interested.) Maybe you can do the same. If you don't like this girl, then move on and try not to worry about it. Okay?

Yes today I went to my classes. I casually met 3 new people, and I think one of them is interesting and I really want to talk more with him! This girl sat in a different place with her group and I had the feeling that she was saying to them "look it s that weird girl" but since I'm really sensitive to criticism maybe I'm making that up. But I had the sensation of being weird. But luckily these 3 new people were gentle, not judgmental, and I think one of them is like me, introverted and with social anxiety! So it's like I lose that girl but new things came to my way...I didn't like that girl that much so it's good in a way that I lost her. I know that it's weird to avoid her, like I don't want to be seen as mean, but she was the first that kept avoiding me, and her actions triggered my anxiety so badly!

You do seem too sensitive about it and maybe pushed yourself into going near her that one time on her bday when it wasnt really comfortable for you. If it were me, if i felt i wasnt going to be able to speak up to someone cause we didn't click well I wouldnt bother or care that they went their way and I went mine. She started 'avoiding' you as you call it because you guys werent on the same page so why bother keeping up some awkward thing. You said you eventually just kept quite around her.. so its a lot more of a matter that she just moved on to have conversation with others rather than was purposely 'avoiding' you. Did you really want her to sit and stay by your side when you just didnt talk to her anyway? That's not fair to her or you. She was better off going her seperate way. and its not bad that you didnt care for her. You will meet people you like who feel the same back.