I know I should have created a child theme, but as they say, shoulda coulda woulda. Learned my lesson, though!
I made copies of relevant code changes made to the function, footer and style files for reference. I deleted the theme from my local files, then downloaded it and moved it to the local theme file. I lost the changes I was trying to save, but at least it kept all my other customizations. I’m going to redo these changes from scratch, so as not to repeat the same mistake.
Thanks!