What does "waddling high" here mean?

Native speaker’s answer
Rebecca
"Waddling" and "high" are not connected here. "Waddling" refers to taking short, unbalanced steps that cause a person or animal to sway back and fourth. Here, he is referring to when she was a child, and children often "waddle". "Yay high" here means "this tall". Again, he is referring to when she was a child.