Hello kipsy,
Thank you for using Apple Support Communities. Sounds like your Photo Stream isn't updating. It also looks like you've done a great job in troubleshooting this issue as well. From here, we'd like to share a helpful resource that has some great troubleshooting steps you can attempt. These steps might be able to help you. Click here:
If My Photo Stream isn't updating - Apple Support
On Mac
1.) Make sure that your Mac is connected to the internet.
2.) From your Mac, choose Apple menu > System Preferences, then click iCloud. Make sure that you're signed in with the same Apple ID on all of your supported devices.
3.) Open the Photos app. Then choose Photos > Preferences. Click iCloud (or Photo Stream).
4.) Make sure that My Photo Stream is selected. If you don't see this option, turn on iCloud Photos to keep your photos and videos in iCloud instead.
5.) On the device that captured the photo that you're looking for, close the Camera app. (Nothing uploads to My Photo Stream until you do.)
You can also try connecting to a different reliable Wi-Fi network to further isolate this issue. Also, if you have any pending updates, it would be a good idea to install them. Keeping your Mac fully updated can help resolve various issues. Just in case, this resource can guide you through the update process: Update macOS on Mac - Apple Support
1.) From the Apple menu in the corner of your screen, choose System Settings or System Preferences.
-If you chose System Settings, click General on the left side of the window. Then click Software Update on the right.
-If you chose System Preferences, click Software Update in the window.
2.) Software Update then checks for new software.
-If Software Update finds new software, click the button to install it. The button might be named Update Now, Upgrade Now, Install Now, or Restart Now, for example. You might then be asked to enter your administrator password.
-If Software Update says that your Mac is up to date, then no new software is currently available for your Mac model. Software Update shows only software that is compatible with your Mac.
Feel free to keep us posted on your results. Thank you for using Apple Support Communities.