D., the best thing you can do is talk to your ped about what is happening. It could be that she is not feeling well.. The ped can help determine that. If you keep a food diary that details what time and how much formula she drank, that would help. Also write down wet and dirty diapers.
Please stop bringing "maybe my baby doesn't love me anymore" into the conversation. With YOURSELF or with anyone else. First, that's ridiculous. She's 4 months old. Have you ever heard that a 4 month old doesn't love her mother? Babies are just little bundles of life and they eat, sleep, poop, pee, giggle once they get old enough, look into their mom's faces, and need to cuddled, talked to, sung to, and loved on. That is THEIR particular brand of love. If they don't sleep well, if they don't eat well, if they cry, if are off their feed, it has nothing to do with love. So put that silly notion away.
Reading about baby development would help you be more informed and understand what babies are and aren't capable of. Please do that.
Good luck with the baby's formula,
Dawn