No worries. It's tough to get to a point where WDing is a natural, reflexive thing for you. A lot of players struggle with this when they're working on improving their smash game.
The advice I always give people if they're having trouble is to play as Marth, because WDing backward and then fsmashing is a really simple, satisfying way to glue everything together. You might not need to do this, though, cause Luigi has an insane WD and there's a ton of great options he has with it.
Just curious - how good's your consistency? Can you WD reliably now, or do you still miss it every now and then? Everyone flubs a WD here and there, but if you're missing 1 in every 5 or something like that, it could be worth it to just focus on actually WDing successfully in matches.
Luigi would be good practice for this. You could get up in someone's face, and then WD backwards to retreat. If you get to a point where you start doing that consistently, you might feel more comfortable with all the characters.
And then maybe what you can do is play a character you're less comfortable with that still has a really nice WD, like Samoose or Ice Climbers. You'll be out of your comfort zone, but still playing someone where the benefits of WD are clear.
Also if you need someone to play against let me know! I'm still working on WD myself (I main DK so it's always been a kind of weird tech for me, which is why I practice my WD on characters like Marth and ICies mostly), so we might be around the same level.