iPhoto for iOS is no longer supported nor works in iOS 8 and has been dropped from further development by Apple. This Apple document describes how to migrate photos from iPhoto to Photos: Migrating from iPhoto for iOS to Photos on iOS 8
It's a whole new ballgame now. Here's some info on how the Photos apps now works.
Your photos are still on your phone. With iOS 8 there is no My Photo Stream or Camera Roll any more. The MPS has been replaced with the Recent Activity album.
The CR is replaced by the Collections mode. The closest we can get to the Camera Roll is to turn off the Summarize Photos feature in the Settings/Photos & Camera pane and view the photos in the Collections/Moments window. 😟

The photos will be in chronological order when scrolled up from the bottom of the window.

The Recent Activity album is showing the photos added in the last 30 days going back to 8/20 (today being 9/18). In iPhoto on a Mac the My Photo Stream is showing more like 31 days, 8/19 to today, 8/20. It must be how the two devices calculate the last 30 days.
WARNING: If you use iTunes to sync photos between your iPhone or iPad and your Mac do not activate the iCloud Drive. Doing so will kill the capability of using iTunes to sync with your mobile device and disable Documents & Data syncing for your iCloud account on OS X Mavericks and earlier Macs, as well as iOS 7 and earlier devices.
