A.M.
Congrats on the new baby! I remember it being sort of on and off with my DD too. I would make sure she isn't too tired at the time you are trying tummy time. Right when she wakes up and has a bottle would be good. But if she doesn't like it anymore, I wouldn't worry about it let her do something else and just keep trying it occasionally. I was trying to do it every day, 2x for 10-15 min each right from the start because the books said to do it daily. My DR told me to give it a rest and lighten up!