Use graph paper draw the room to scale now cut out the toilet, the vanity and the shower move the pieces where yo think they will fit starting with the toilet since that is not changing. I use carboard for those pieces to keep them lasting for a while . A free standing tub needs a min of 12” around it to be able to clean the walls behind it so make sure you allow that then figure where you will walk around. I can’t see where the tub could go.

Just completed our similarly sized master, getting rid of a massive corner garden tub. This was our prelim sketch. We ended up pushing the shower further to the right and enlarging the toilet space. The shower is not quite as deep as we wanted due to the window placement, but we are still thrilled with the results!