Iphone

My iPhone 11 plus never seemed to be set up right. no matter what I do I can't back up to the iCloud. I see my devices connected, don't want to log in and out because i'll lose everything on there. says it will connect and back up when connected to power source and wifi. It is and still won't. now my phone is constantly flipping out and telling me to back up. I'm trying but it just won't.