I can't back up my iphone

I am very confused.

• “I am [on] iOS 17.3.” This iOS version was superseded on February 8, 2024. Seven subsequent iOS 17 releases occurred, followed by iOS 18. So you are way behind.
• ”It says it is backed up …” Nothing you presented shows this iPhone was ever backed up. You did show an iPad that was backed up.

iOS 18 offers good ways to manage your iCloud storage, that are somewhat different from iOS 17’s methods.

Well, we now know nothing more than we did after your original post.

A few examples of additional helpful information you might offer:

• How much iCloud storage do you have? You said “I just bought additional storage.”
• How much iPhone storage are you using?
• You said “I keep turning on the back up this iPhone” but previously you said you could not turn it on.
  • What happens when you try?
  • What works?
  • What fails?
  • What error messages appear?
• Is your Wi-Fi free of anti-virus? Of VPN?
• What other pertinent information should we know?