Do you have another tub in the house (so loosing this one won’t hurt resale)?

Yes, there is one in the bathroom for the other bedrooms.

What’s behind the slanted wall?

It is my husband’s closet. Originally we imagined we’d expand the bathroom and take it over. Now that we’ve had separate closets for 10 years, we’re not interested in sharing and, really, there isn’t enough room in mine anyway. I wonder about taking some from the wall by the shower and extending the Left wall at the entry to eliminate slanted wall altogether?

And then do something like this where the shower is now? This is the first example I found, but I would want our shower to extend farther out. How much room would I need for a toilet alcove and reasonable shower width?

Oops forgot the photo

Is this bathroom accessed from inside your bedroom or from a hallway? Could you move the entry door to one of the other walls - the wall where the shower is or the angled wall? Or, would that be totally weird?

Unfortunately, the current door is the only possible entry point. Behind the angled wall is a closet. Behind the shower wall is another bedroom.