N.W.
My daughter is 5 mos. My pediatrician advised (with my 4 year old too) that you cannot spoil a baby under 4 mos. Until that time you can feed them as often as they need, hold them, rock them to sleep, etc. Around 4 mos they usually don't need to eat at night and should be placed to sleep drowsy so they learn to fall asleep. If she isn't really eating, she may just need to be rocked back to sleep. She is still too young to "force" to sleep.
Good luck.