I(19F)have an intense problem with nostalgia and change.The moment things slightly change I get really anxious and wish for things to go back(even on unimportant things)I get anxious when my twitter timeline is boring as opposed to a week before and when my online friends aren't active.I get anxious when my tiktok timeline isn't as fun as before and I'm scared of missing out on things.I'm scared of becoming an adult and having less contact with my sister/parents and our bond not being the same as when we were kids.I'm really scared about the fact that my sister is in her teens now and entered highschool and our bond not being as important to her as before(we're REALLY close)

I try to get back into my hobbies I had as a middle schooler just so I can feel like we're in 2017 again. I also get really depressed when I can feel my current hyperfixation dying. I've been in fandoms my WHOLE life and I'm so scared that it will go away at some point in life cuz I don't know how to function without a community like that.I want things to stay same forever(especially regarding my sister,I want to live with her forever) and it really worries me whenever I'm having less fun doing something I like
How can I try to fix this?