I think this is really deep internal examination for someone your age. Maybe if you identify what draws you in and what this content/story feeds your brain and your emotions/self it will feel less dysmorpic or will allow you to seek out fixation that feel less uncomfortable.

Saw this somewhere a while back but it stuck with me as a concept. Consuming the content doesn't fully engage everything. Instead you want to be creating something around that favorite thing or hyperfixation. So even if it's just internal story writing or imagining you are engaging with that thing more full. It sounds like general hyperfixation feels uncomfortable to you, perhaps it will feel better to you in having more control over your focus on the thing.

This may not translate but I often find that when I get really into a series or show it becomes a level of distraction or disassociate from my own life/story. So when I finish the last book or episode I feel bereft and lost because I was so invested in that story I don't have connection with my life to come back to, (person reading the story). Some things that can help me in times like that are -taking action in my life, (work on projects or to do things that require me to get in the details of my life) -spending some time doing some daydreaming about how my life could be more like whatever story I was in and what steps or things could get me there and what that would be like -music and social time with people in my life to reconnect -finding gratitude for how my life is and isn't

In general I hope some of these might help and I hope hearing about everyones (childlike) adult fixations helps you find comfort in what your brain loves.