Gas cues vs hunger cues?

My baby is 3 weeks old and formula fed. I can usually always tell when she's hungry, since she eats every 2-3 hours on the dot. But lately when she starts acting hungry and I start to feed her she is grunting and pawing her hands and swinging instead of pulling them towards her face like she normally does when she's hungry. She can't swallow while she's grunting so she always spits the milk out her mouth or chokes on it. Then when I pull the bottle away to try and ease her tummy, she gets frustrated because she's also hungry. Even after all the grunting she doesn't get any poop or farts out. What is she doing and what can I be doing to help her? I feel so frustrated too when she does this because I can't understand her cues or what's wrong with her :(