What do you do when your 4-month-old baby starts to bite your nipples?

My baby's 21 mons old already & she had a habit to bite and pinch my nipple while breastfeeding. I talk to her and tell her that "nanay is getting hurt". If she will not stop, I will slowly remove my nipple and tell her that she cannot have "dede" if she will continue to bite my nipples. It's effective. Doing this since she was 6 mons old.