Overrecting?

So today I was out to dinner with my family. I had my 3 month old daughter with me and my mom kept insisting I give her a bite of ice cream. I told her no she’s too young and I don’t want her to have sugar. She goes behind my back and give her a bite. I told her until she respects my decisions don’t come around. She got mad and told me I’m overreacting. I feel bad but i felt it needed to be done. Am I overreacting? I just feel she’s way too young she’s not even old enough for rice or anything. TIA