Update My Photostream in Photos
I updated to OS X Yosemite a few days ago and in the process lost iPhoto. I had My Photostream set up to sync photos from all my devices. I noticed that there is a My Photostream folder in the new Photos app too, but it doesn't update. The photos I took with my iPhone since the OS X update and since iPhoto was replaced by Photos have not yet been synced to My Photostream on my Mac, although I can see them on my iPhone and my iPad in the My Photostream folder.
How can I get this to work again (without having to pay for iCloud online storage)?
MacBook Pro (15-inch Mid 2012), Mac OS X (10.3.x)