G.B.
The cereal is making her fat. She doesn't need it. She is not getting enough nutrients now since she's filling up on cereal. I think it's probably plugging her up inside too so she feels full all the time.
Formula and breast milk should be their first food and only food until they are older than this. Baby food and cereal are only fillers, they are ONLY for teaching a child to chew and swallow, they are NOT for nutrition. They are empty food. Flavored goo. NOT for food.
So by giving her cereal you are keeping her from getting nutrients she needs to grow and develop her brain.