breastfeeding advice

Molly • I first became a mom at 16 to a handsome boy, 11 years later & we welcomed our second. Now I have my boy & girl! :).
Hey mamas, my daughter Madeline is 3 weeks old, she is gaining weight but she just seems to always be on my breast and never satisfied unless I pump. How do you ladies up your supply? Thank you in advance. I'm a second time mom but first time breast feeder.