Why aren't all my pictures going to iCloud?
I had issues with the iOS 6. So after I backed up my phone, restored it as a new phone, not all of my pictures showed up in Photo Stream.
iPhone 4S, iOS 6
That's because you've already setup Photo Stream up-on registation the iOS 6.
If you want to delete your photos from iCloud you can check this article there is informations that's helpful here it's http://support.apple.com/kb/HT5125
Good Luck.