AITA Bathroom Boundries

I, 59 yr female, in good apparent physical health (important later) was attending an event this evening. I needed to use the restroom, as one does and since toilets in public bathrooms are lower than standard toilets, and I have had both hips replaced, I use the handicapped stall. Almost impossible for me to get off a standard public toilet. The first time I went in the bathroom, a mother and her 3-4 year old child came in the bathroom. Both standard stalls were empty. The girl begins to bang on the door and tell her mother that she can only use the “big one”. Her mother told her someone was in there and she cold use the smaller one. The child then bangs on the door and loudly says she “has to go” and needs the big potty. I tell her I will be a minute, finish, and then wash my hands and leave. Later in the evening, I return to the bathroom and have not even pulled down my pants, and in comes the mother and child. The child immediately bangs on the door, in spite of the other 2 stalls being empty, and insists she has to go now, and can’t wait. I pulled my pants up, because I now cannot pee with all the commotion, and step out of the stall. I addressed the little girl and told her some people really needed the “big potty” because we have health problems and can’t use the small one. Her mother told her to go on in, looked at me, and said “well she has to go a lot”. No apology, no correction-no peeing for me. Y’all I raised 2 daughters and never would have tolerated this behavior. I would have told my daughters to use one of the other available stalls. AITA for saying telling the child that other people need the big potty?