Photos on iPhone won't upload to iCloud

I have two iOS devices login the same iCloud account, iPhone 4s (iOS 7) and iPad (iOS 8.1).

The iPad has about 650MB photos and that's the same as photos in my iCloud.

The iPhone has 4.7GB photos in two folders, camera roll and photo streaming. The photos in camera roll are not in iCloud at all, and photos in streaming folder only have a few uploaded into iCloud.

But in iCloud storage settings, it clearly shows 4.7GB photos from iPhone are backed up.

I have a guess that the iCloud is updating corresponding with the iPad not the iPhone. But I want all photos in my iPhone showed in the photos of iCloud, how to do that? All auto-upload/back-up options are enabled.

Thank you so much.