Tugging at the breast

Starr • Selenya Avery born July 24, 2016! 🎀 Angel Baby Lily🌸👼🏼 Secilia Elizabeth born October 15th 2021 🌈💖 Baby #3 Due June 2025! ❤️
What does this mean? My 3 week old pulls her head back and takes my nipple with her, and pushes her hands against my breast. Also, her lip quivers at times. I read this stimulates the let down. Is my supply low??