Hey @craiginker great to see ya on the forum again my friend! I believe part of what I think you’re bumping up against is that it’s tough to be really expressive with the song in 1st position.
If you can do the -3" whole-step bend, playing it in 2nd position on a country-tuned harmonica will offer you a lot more expressiveness as I demonstrate here:
The -3" is not for the faint of heart tho! I’m guessing if you’re like I was for the first couple decades of playing harmonica, that’s a bit too intimidating. In that case, you might consider a Lee Oskar Melody Maker harmonica, which I demonstrate here:
Otherwise, maybe this post on vibrato is helpful?