why did I lose my period

I'm hardly even underweight and now I eat thousands of calories a day. I used to not😶 but now I'm healthier. I'm also mostly vegan except for b/ps. I haven't had it since September 5th of this year so almost 5 months. Tbh it's kind of great not having it but it makes me worried. I also lose a lot of hair and don't get discharge even though I eat so much and am gaining weight. I'm 14 if that helps.