Stuck in the loop

This is was me last year. I just got my Cambridge interview this year for Land Economy yesterday. What helped me break out of the loop which, I must add, may not necessarily work for you, is actually visiting the universities I wanted to go to. Making it real, being able to physically touch brick and stone of the universities jump-started me. It made me realise that if I wanted them, I would have to get out of my loop of self pity and anxiety. If you have/worry that you have a mental disorder affecting you PLEASE start sorting that out now via therapy, talking, whatever. It will only compound later.
What's more, I beg you, do NOT get hung up on supercurriculars. For this year, start very small. Search up a random economics topic right now and read one article on it (even the Wikipedia page counts). Take one aspect of it that you found interesting and research deeper into that. A few days later, watch a youtube video/university talk about it. Boom. That may be one paragraph of your personal statement done in a week. With supercurricular activities, just sign up for stuff you like in sixth form and relate them back to economics later. Like sports? Play some sport all year and then find out about the economics of massive sporting leagues. Can their popularity be explain by any economic theory? Learn about that theory and so on and so on.