I Am Horribly Insecure About My Appearance

I feel fat. Whenever I see my reflection I want to die because of how ugly I feel. I’ve put on 20lbs in a couple months and I hate it. All I do is obsess over my body before I leave for school or work. I look disgusting and gross in everything I put on. My mom even commented that I look like I’m gaining weight. I’ve always been relatively average my whole life and now gaining weight is so hard.