Icloud syncing problems

Hello, I have recently purchased the extra 50GB of storage on icloud for my iPhone 5 ios 8.1.1, to ensure that my photos are being backed up. Initially everything was backing up and automatically syncing to icloud, however the last 300 or so photos and videos that have been taken in the last week have failed to upload when connected to wifi. I am not sure how to get my phone to continue to sync automatically when it seems as though I have all the correct settings selected.