My LO also used to have heavy breathing with feeds at that age. It got better after the first month. If your baby seems to be turning blue or is struggling to breathe for a prolonged time, please seek medical help urgently. Oh.. my first daughter had one episode of choking on breastmilk which led to her not being able to breathe for a short while. I did the baby Heimlich manouver on her to get the milk out from her airway. It’s useful to learn lifesaving skills for our babies:) (she’s fine, by the way. Settled it in under 10 seconds. She’s 4yo already. Haha)
Yes, same as my LO. Don't worry too much, their lungs are the last organ to be developed and hence may be result in heavy pants. It is normal
Probably your baby is tired sucking. Let your LO rest for a few seconds then continue feeding.