Why do babies fight their sleep 😒

My baby has been doing this for a while now she usually takes 2 naps a day but always tries to fight her sleep , will go up to 3 hours past her nap time then get really fussy and cries I try getting her to nap when it's nap time but she refuses to sleep and I know she's tired because she starts laying her head against my chest and rubs her eyes. 3 hours past her nap time I give her a bottle and she goes right to sleep giving her a bottle which is what I try doing when it's her nap time. Am I doing something wrong ? It's like drink the damn bottle and go to sleep! (I don't mean it in a bad way but I have things to do like clean, do laundry and eat)Â