Why does my mom think I'm not eating?!?

I'm 13. I'll admit in the past I used to try to starve myself, but I have a therapist and a nutritionist now and I know it's bad now, so I dont. I'm honestly getting better, and following everything the nutritionist tells me to eat. For some reason my mom thinks I'm not eating enough just because I don't want a snack for instance. She said she doesn't like what they're telling me, but I'm eating FINE. For breakfast I had special k cereal with skim milk with a cut up banana. For lunch I had a peanut er sandwich, a peach and a cheese stick. And I didn't have dinner yet. How can I convince her I'm fine without eating a thanksgiving feast?!