Text Message Forwarding option not showing

RESOLVED: My iPhone 11 with software 14.8.1 isn't showing the option to turn on Text Message Forwarding. I think I turned it off, not knowing what it was and now I can't get SMS texts to/from my MacBook Pro, but the option to even turn it back on has disappeared. What do I do (in simple terms, please) to fix this, please?

I had repeatedly turned the iPhone off and back on and it didn't show up, but I tried one more time after posting this question and it showed back up, already turned on. SMS texts are now going to/from my laptop in addition to the iMessage. (Rhetorical question: why did it *finally* show back up, and turned on at that? The phone did happen to be in Settings>Messages when I turned it off...)