Iphone 6 icloud won't back up

My iPhone 6 will not back up. I have deleted about 200 photos, and now I only have about 600 photos in my gallery, and I have deleted apps. When I go to see the amount of storage I have it is in the blue and not in the red, so I was assuming I had enough storage for a back up. When I go to back it up it still says not enough memory. I do not understand how I do not have enough memory, or what else I am supposed to delete.