Overreacting?

Hey guys, apologizing in advance for the rant, but I need some advice. Am I just overreacting? I got two things. I am a 17yr old girl, who is awkward at party’s, dancing and anything that involves talking to people. First off I am quite insecure about how I look and act. I find myself comparing and wishing I was like someone else. I find myself dreaming about ideal situations and thinking back on what i could have done better. I feel just average. Like I don’t think my friends would notice if I stop walking beside them. I have quite a few medical problems and this year am getting surgery causing me to kind of feel like an loner whenever I go back to school since I have no idea what’s happening. Sometimes I just want to disappear from off of the map. Secondly a formal is coming up. Since it is are last year the group is having a get together before formal and an after party. While I been out of school they have planed this on a group chat that I am include in. I was talking to a friend today lily and she ask if I am going to do the dress reveal with them before formal. I said I think so and she said if I got invited to let say Ava’s house so we can do it. She show me the fancy invite she got I did not get it. I am not that close to Ava like I didn’t know she had a boyfriend untill a friend told me a few weeks ago. And I guess I don’t really hear much gossip either. Like I said I am just there. Well this friend I was talking to let’s call her Lily she said she would bring me as her plus one since I didn’t have the fancy invite. I ask Ava hey is there anything happening at yours before formal she said yes but only 6 people can get dressed at hers but I can come after. I sent a screenshot to Lily and she said that’s bs and really mean to be just leaving me out. I asked Ava the next day is anyone else not getting ready at yours just wondering so I can get ready with them. She then said nooo girly it’s all good you can come to mine i just had to “double check with my mum”. Like girl if 6 people are getting ready at your 6 people the whole friend group bug the last person can’t like what. Anyways I don’t know if I should go now I feel like I wasn’t invited at first. Should I go?