The act of restoring wipes off the data on the phone and then you reloaded an old backup from itunes that didn't have the pics you took on the new phone. If you had icloud and photo stream activated on the new phone and still do you can get the new pics the next time your phone syncs with the cloud.
3 conditions have to be met to sync with the cloud.
1. phone must be plugged into the wall or computer.
2. wifi must be on
3. phone must go into sleep mode
I couldn't agree more. Restoring erases the data that is on your phone and reverts it back to how it was when the backup was created. If iTunes did an automatic backup, you would be lucky to get your photos back. You can check for saved backups using iPhone Backup Extractor. It can also extract photos from an iTunes backup.
It sounds like you transferred the backup from the lost iPhone to the new iPhone.
The first time you connect a new iPhone to iTunes on your computer that was or is used to sync with another iPhone or iOS device, you are prompted to transfer the backup for the other iPhone or iOS device to the new iPhone, or set up the new iPhone as a new iPhone. This is designed to be done right away after purchasing a new iPhone, not days or weeks later. The former is not involve restoring the iPhone with iTunes but the effect is the same. Photos/videos in the iPhone's Camera Roll are included with the iPhone's backup.
When choosing to transfer the backup for another iPhone or iOS device to a new iPhone the first time the new iPhone is connected to iTunes on your computer, you are replacing the photos/videos in the new iPhone's Camera Roll with the photos/videos in the backup for the other iPhone or iOS device Camera Roll that you chose to transfer to the new iPhone - along with all other data included with the backup for the other iPhone or iOS device to the new iPhone. This does not a merge or add to the existing data on the new iPhone, this is a replace with the data included with the backup for the other iPhone or iOS device.