I know this might not help, but please, please know that a bright future is possible. From age 13 to 20, I had extreme depression, anxiety, and an overall mood disorder. I spent a lot of it, well... being depressed in my room. I was overweight, had -10/10 self-esteem, and no true passion. I also had an eating disorder for 5 years, and attempted suicide. It wasn't until I went to university that things started to noticeably change. I started coming out of my shell, and surrounded myself with topics and people who interested me. My moods were still fluctuating, but I worked very hard at maintaining my life on the outside. It got so bad last year that I forced myself into counselling services at my school. I ended up getting diagnosed with Bipolar type II and got professional help and medication over the summer. Now? I have my depressed days here and there, but I am so happy with my life and where I am heading. Please know that healing is a process. Building a positive and new lifestyle will take time. You will have dark days, and you will lose motivation. But keep going. A new life will not happen over night. Life is not a destination - it is a journey to be walked, and a space to be lived.
I really want to give you step by step advice, but please reach out to a professional. My life did not drastically change until I saw one. I only wish I went sooner. Some of them suck, but many genuinely want to help you.
However, for now, I can suggest a few small changes:
Go for a 10 minute walk after you wake up. Do this every day. You can make it longer. You don't even have to walk some days if you don't want to - just go outside and inhale some fresh air.
Call up a family member and ask them to join you on the walk.
Attend a community event, e.g. community lunch, dinner, games night.
You are young, and have your entire life ahead of you. Please know that purpose is possible. Sometimes we just have to dig through layers and layers of dirt to find the treasure.