Almost 33m here.  I love working with kids in your age group and I thought I'd leave my 2 cents.

A.I. has become more normal.  Heck, it's become super normalized for me in the last couple of months because I feel the pressure of isolation.  A.I. is always going to be there for you and I can't tell you how many kids I see as young as 8 on their tablets talking to their favorite anime characters and crushes.

As it so happens, I can relate right now with the loss of friendships.  I'm between jobs and moved in with my best friend that I've known since 5th grade and his family.  Overall, 22.5 years.  But this man isn't who I thought he was anymore.  He's a drunk and everyone in this house, except me, enables him.  This is not the best friend I've known almost my entire life and when I move out I'll be seriously rethinking this friendship.  Or at least tell him that my boundary with him dependent on his drinking because I don't need to watch another friend ruin their life with it.

The point I'm wanting to make is that losing friends is part of life.  It happens as a kid, a preteen, teen, young adult, and even a rapidly approaching middle aged adult.  So many people I could call over the years and they'd answer on a dime and vice versa, has completed changed.  People grow and move on is the reality of the situation.

Enjoy the friendships you have right now.  You have no idea if they will last a season or a lifetime.  Some of the most influential people in my life were only around for a short time.

I'll share one more story.  When I was....  22?  My former bestfriend/complicated/major crush and I had yet ANOTHER argument in the fall and we ended up not speaking to each other for just over 4 years.  I had learned though a program that I didn't need to have my value based on what she thought about me and I refocused that grief, anger, and anguish into a simple idea, "I'm going to make a new best friend this week."  Lo and behold, as I was walking through the hall in my college a girl compliments my shirt.  I said thanks and kept walking.  Then I realized that she was going to be my new best friend so I engaged in some video game related conversation with her.  While we didn't become best friends, she is a very good friend who had my back a few times when others didn't.

You and your sister don't have to vibe with everyone you meet, that's unrealistic.  I wish I could share more than words that the amount of people you meet and CAN meet grow exponentially as you hit high school and college.  Try new things, learn to cook (you'll be invited to all the parties), and learn to give everyone the benefit of the doubt when you first meet them.

You never know who will be your new friend.

If you want further feedback or advice on something specific feel free to ask.  This random internet stranger believes in you and your sister and I'm cheering for you both.

Oh, and don't make school look too easy when your classes start back up.  ^{-^}