How to explain to my Mom that I want to stop taking weight-loss injections?

I (18M) am class III obese (BMI 40.3).

My Mom has wanted me to take weight-loss injections for a while (a lot of people in my family have in the past few years, including her and my father, all successfully losing 50-150 lbs). I told her that I didn't want to take weight loss injections, but she kind of had a breakdown about how she's so worried for my health and how with me going away to college in a few months she wants me to lose weight and be healthy. Without talking to me more about it, at my first doctor's appointment since I turned 18 (about a month and a half ago) she asked the doctor to prescribe me a weight loss injection.

I've taken a few so far and I hate them. Injecting myself with a needle makes me queasy, I feel sick afterwards, one of the potential side effects is a depressive mood. I'm diagnosed with ADHD and depression, but I don't take medication for either because my Mom thinks doctors are too eager to diagnose children and prescribe them medications they don't need. While my depression's mostly gotten better in therapy, I'm terrified of ever feeling again how I did during my worst depressive episodes.

But I have lost ~7 lbs in the past month. And my mom wants me to increase my dosage because the injections are expensive so if I lose weight quicker it won't cost her as much money. (Which I found odd, because my parents are actually very wealthy, and I suspect she just wants me lose weight faster so she can stop having a fat son). I don't want to keep taking weight loss injections and, honestly, I don't want to lose weight. I know I need to for my health, but I work out, and even though I have a high bf%, I like the aesthetic of being a big, strong guy. I'm also embarrassed. I keep thinking about losing more weight and then my friends or girlfriend asking me about it and having to tell them it's because I took weight loss injections.

The thing is I know she'll have a breakdown if I tell her I want to stop taking them. I'm just so sick of feeling like she controls my entire life and I just have to sit there and do whatever she wants me to do.

Maybe this ended up being more of a rant than an ask for advice, but I'm just at such a loss for what to do.