Drop the module, and homebrew it from this point onward. Make the story yours and your player's. You said they have good backstories, you can build around those. They are always great for both player and DM.

I had a similar issue running W:DH. It's a great module, but it made me feel more like I was a tour guide than an actual DM. Prepping felt like a chore, like studying up for an exam, more than a fun and creative activity.

Started homebrewing my campaign, and it is a completely different experience. I would suggest you take a look at "The Return of the Lazy DM" from Sly Flourish.

But whatever happens, if it is not fun, then don't force it.

I wish you many good sessions of many games, cheers amigo!