Photo library will not fully upload to iCloud from computer
I know it may be a little too late to answer but, if you haven't found out a way to get all of your photos to your ICloud, here I how:

You must transfer all photos from PC to Iphone through ITunes.  You should have a photos tab that you can select after connecting phone to pc.  You must check the box that say sync photos and make sure you select the radio button where you can pick which folders you want transferred over.  Unless you want your WHOLE library.  After you sync your photos, create a new album on your phone and SAVE those photos to it.  

Icloud photo library will only upload photos that were TAKEN or SAVED to the phone.  Once you save your photos, go ahead and use icloud photo library to upload those photos to Icloud.  To view among all devices, make sure Upload to My Photo Stream is on.  If you want to share photos, make sure ICloud Photo Sharing is on. 

Im a Technical Lead for a well known cellular company and have done my own research, troubleshooting, and testing to confirm this information.