In English, there are certain body markers we use when comparing height to someone else. We avoid comparing to body parts associated with sex or sensuality. Here are a few ways to compare height:
“I have clear memories all the way back to when I was no taller than my mother’s knee.”
“I have grown some. I’m nearly up to my mother’s waist now.”
“I am shoulder-high to my mother.”
“I can nearly look my mother square in the eye now.”
“My mother only has a couple of inches on me now.”