I'm a 13 year old girl and I don't know if I know how to stop.

I'm 13 and recently I've been stockpiling everything I buy, I get food and I eat less than half and then say "I'll eat these leftovers later", but never do. Clothes? I buy as much as I can, even if it's not my style and I'd never wear it. I have clothes I've never worn, clothes that I bought years ago that I haven't grown out of. I have so much stuff I'm drowning in it, but I don't know how to make myself throw it away. I feel guilty throwing away food, and the clothes I just feel bad getting rid of it when it's new even if I've never worn it. I want to become minimalist but I don't know know where to start. Any advice would help.