If you were using Optimize Storage, then the full sized original files weren't kept on our phone, but were stored at iCloud.com. If you then turn off iCloud, you get a warning that says that the smaller files on the phone will be deleted, and the full files will remain at iCloud.com for a month.

Is this what you are referring to? And you didn't choose "Download Photos & Videos?"
Do you have enough storage space on your phone to hold all your pictures? If not, you can download all your pictures to a computer by going to Photos at iCloud.com.
If you have room on your phone, then you may be better off just by turning iCloud back on and then off, but choose Download…