What does this mean?

So I’ll go all day starving myself because everytime I look in the mirror I see a body that I don’t like but then eat at night, and once in awhile I’ll eat a bit more but I can’t eat more than like a few chicken nuggets or something or I’ll get sick. What do I do? I’m really worried and I don’t know what to call the thing I’m doing. It doesn’t help hearing my mom talk about how I always eat (I don’t, she’s never home so she doesn’t know) and then saying how my sisters so skinny.

ETA: I weight 123lbs and my sister is like 111lbs or so, her and my mom always bring up how I have to wear a size bigger than her, I don’t think they mean harm by it, but I already know I’m bigger I don’t need a constant reminder