Are you looking to use some of the space with the steam shower?

If you have another bath with a tub for soaking don’t add tub here. A free standing tub in a shower requires cleaning tub and shower with every shower use, including the harder to reach areas on sides of tub,
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Turn the toilet to face the sink wall and put a tub under the window.

There really doesn't seem to be enough space to add a tub unless you steal space from another room. Is that a possibility?

Tub won’t fit under window. The width of the room is only 7ft. The aisle wouldn’t be wide enough with the sink, aisle then tub. The shower area is larger than we really need.

Stealing space isn’t going to work.

I’m just looking for ideas….so far it seems Norwood is correct that there just isn’t enough space.