Macbook Pro using all the bandwidth My Macbook Pro is using all my bandwidth and making my entire network unstable.

I thought this could be the iCloud Photo Library, so I paused for a day, didn't change anything, turned off iPhoto process, no change. I disabled iCloud Drive, same issue.

Regarding Activity Monitor, this is most likely because of nsurlsessiond,
Regarding my router :

2015-12-21  10:39:48    Kevins-MBP  s3-3-w.amazonaws.com 
2015-12-21  10:39:37    Kevins-MBP  gblon-edge.icloud-content.com.akadns.net
2015-12-21  10:39:31    Kevins-MBP  s3-3-w.amazonaws.com
2015-12-21  10:39:24    Kevins-MBP  gblon-edge.icloud-content.com.akadns.net
2015-12-21  10:39:21    Kevins-MBP  gblon-edge.icloud-content.com.akadns.net 
2015-12-21  10:39:19    Kevins-MBP  gblon-edge.icloud-content.com.akadns.net 
2015-12-21  10:38:41    Kevins-MBP  p04-ckdatabase-current.edge.icloud.apple-dns.net 
2015-12-21  10:38:26    Kevins-MBP  p04-keyvalueservice-current.edge.icloud.apple-dns.net 
2015-12-21  10:38:24    Kevins-MBP  p04-keyvalueservice-current.edge.icloud.apple-dns.net 
2015-12-21  10:38:23    Kevins-MBP  p04-contacts.icloud.com 
2015-12-21  10:38:21    Kevins-MBP  p04-keyvalueservice-current.edge.icloud.apple-dns.net 
2015-12-21  10:38:11    Kevins-MBP  keyvalueservice.icloud.com 
2015-12-21  10:38:10    Kevins-MBP  p04-sharedstreams.icloud.com 
2015-12-21  10:38:09    Kevins-MBP  stats-public.grammarly.io 
2015-12-21  10:38:04    Kevins-MBP  p04-escrowproxy.icloud.com 
2015-12-21  10:38:00    Kevins-MBP  p04-escrowproxy.icloud.com 
2015-12-21  10:37:59    Kevins-MBP  p04-streams.icloud.com 
2015-12-21  10:37:59    Kevins-MBP  lcdn-locator.apple.com 
2015-12-21  10:37:58    Kevins-MBP  p04-escrowproxy.icloud.com 
2015-12-21  10:37:56    Kevins-MBP  p04-mailws.icloud.com 
2015-12-21  10:37:56    Kevins-MBP  p04-quota-current.edge.icloud.apple-dns.net


I know amazon is probably because of Photo.app / iCloud Photo Library. So is my only option is to turn that off? or could I be wrong?
nsurlsessiond is used by other software to make requests on their behalf, the most common source of large amounts of data being transfered with it on workstations and end-user devices is iCloud Photo Library and iCloud Drive. 

You can watch for filesystem activity in ~/Library/Caches/CloudKit if photo sync doesn't seem to be the source. It is possible to have a condition where sync operations with iCloud Drive don't reconcile as expected and your workstation will be re-fetching data — you will see evidence of this in logs for bird(8) for the user.