Body shaming your kid now?

The last time I've weighed myself, it said I am 40kg while being 5'1. Meaning I'm underweight, and my mother wasn't happy. I mean, why would she be? But she didn't make any effort to help me gain weight. I've always had a fast metabolism, I've never been fat or chubby. I have also been quite insecure with my weight in 7th grade. I was 45kg, while my friends were 40kg and lower. Now, In the 9th grade, I've been walking more and eating less. It worked I guess, but my mom was unhappy about it. Yesterday, my mom bodyshamed me, saying that my breasts were small and that no one would like it. I was shocked, I didn't know how to react. My brother joined in, they laughed, so I forced myself to smile. It really hurt... I've always hated my body, and when I was finally kind of fine with it, they just say that. I don't think I will ever be happy with my body now. I never cared about how I see myself, I only cared about how Everyone else sees me. And if my family thinks that? What the hell do other people think? They also make fun of my face too sometimes, mostly because of my pimples. I want to try to get rid of them, but I always get so emotional looking at my face I just gave up skincare.