iCloud Storage

I received an email that i had used up 75 percent of my data. I determined that was mostly due to photos. I went to Settings> (Your Name)> iCloud> Manage Storage> Photos. If I “disable and delete” documents and data from photos will I lose everything? I only have my cell phone signed into my apple account and I don’t think I’ve downloaded any pictures from elsewhere. It says it will give me thirty days to download everything but if i don’t meet that mark will my photos be deleted?