What is your baby's head measurement

In centimeters if you don't mind. My baby is 41.5cm I am so seeing if that is too small

I know it's growing, just really slowly and it is definitely on the small side. I weighed her and is is 20.8lbs. She says mama dada and kitty. She waves hello, can almost walk (She is using the walker she stands and pushes) and she's very good with her fingers at picking up food. She also knows the word no.

P.s. me and dad have smaller heads but her half brother who is 11 has a huge head