Fussy noisy nurser.. Normal or cause for concern?

My dd is 16d, and for the past 3d she has been "laughing" when I first start to nurse her. It's like she gets so excited she's getting what she wants. Then for first 30sec she grunts (nom nom nom) and when my milk letsdown, she gulps it down with each suck.. Wide eyed. After about a min or two, she unlatches, whines, relatches, sucks a couple times, unlatches, whines, and continues that cycle for about 5min. She also pulls my nipple back and bites it. It's like she's fighting it. At first I thought letdown was too fast but her problem of unlatching and whining is after she gulps. Sorta like when the milk slows is when she's irratable. As if she wants it to continue being fast flow and is mad that it slows. I always keep her on each side for 20 min +/-. She wets plenty of diapers each day so I know she's getting enough. And her poop is yellow so I know she's getting hind milk. She's also quite alert now and engages us so idk if this is just a phase, part if a normal growth spurt, or if something is truly wrong. Any thoughts?