I was pretty much lost from here....

"We picked Hooters because it was a mom and son night and my 3yr old and wanted to treat him for doing well in his baseball"

Actually it sounds like you brought TWO? children? A boy and a girl?

"she still charged me for ordering a childs milk even though she had served her water"

After the waitress explained the process of adding another item to your bill, (she was new, remember) you even said you UNDERSTOOD. I wouldn't be suprised if adding/changing up the order might give her issue and delay something. You even acknowledge she was new yet complain there needs to be training?

The only thing I see here us that they overcharged you a milk, which they fixed.