How can I loose weight?

-Sorry if I misspell anything-
About me: A 16 yr old that used to weigh 160 with a little over regular BMI and probably now weighs 200 with a over BMI. Also I'm 5'4 female
I've also have had problems with body image and starving myself at some points.
So, I want to loose weight because even though I've struggled with my weight my whole life I've gained quite a bit during 2020. I gained at most 40 pounds. It started when I got on the depo shot, I didn't have a choice because it was a requirement if I ever got a boyfriend.
The depo shot caused my eczema to flare, which wasn't found out till my body started getting used to it (8 months later). This caused me to become even more self-conscious than I already was, because my body was all red, dry, and itchy. I started gaining weight as a symptom of the depo shot and because I didn't do anything during the summer because of my skin. I used to live with my dad and almost never ate and drank water, because he never had food except for dinner and even then I lived with 6 kids. Now I live with my mom and I have regular meals... of only lunch meat sandwiches and pizza with pop. On occasions we get some good food. I can't get my own job until I can drive by myself (in March). In march i'm also planning do join a gym with my boyfriend. So this just a background of basic information to see if anyone can help. If you need any other info just ask.
How can I loose weight?
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