iCloud Back up Size

Hi everyone, I'm sorry if this has been answered but I was unable to find it. My iCloud is set up to back up documents and contacts only. The documents is 376KB. However, it is failing to back up as the details under backup states that my next back up size will be 5.6 GB. Previously, i was told that i was out of iCloud space and it was entirely "Backups" and the 376KB of documents. I assume this is reaching the same issue. How can I adjust this size since I'm backing up nothing (to include apps or photos) besides documents and contacts ?

Thank you,