Hi Charles,
Sorry to hear you've had quite some trouble!
Firstly: You've done everything correctly until the point where you wanted to install your custom keyboard layout.
So there's no need to reinstall Ukelele, generate a .dmg file or install from it, etc.
All you need to do is this:
In Ukelele:
• While your layout is open, go to "File > Save …", navigate to your project's folder and click OK to save your layout there.
It'll be saved as a "bundle" file.
(It's good to have a project folder to keep all your stuff together, like notes, icns file, keyboard layouts.)
• Go to File > Install > Show Organiser.
• In the Organiser window that comes up, the left column shows some files or folders. Click the "Set Folder" button there and navigate to your project folder.
• You should see your new layout's name in the left column. Drag it to the rightmost of the three columns – "Installed for Current User".
• You'll be told to log out from your Mac user account, and back in. This is to refresh the list of keyboard layouts MacOS knows about.
After doing that, you don't need Ukelele anymore:
• Go to the System Preferences panel: Keyboard > Input Sources
• There, click on the + at the bottom, because you want to add a new keyboard layout to the existing list of activated ones.
• You'll find your layout in the same language group as the original one you started with.
You can also look inside the Ukelele manual (PDF) you can open through its Help menu, especially section 3.3 (Installing and using a keyboard layout) and section 6.4.3 about the Organiser.
Hope this helps!