What is the purpose of the "vanity desk?" Does someone like to sit down to shave or apply makeup/do hair? Seems like wasted space when you have a large two-sink vanity already. You could put a linen closet in, instead, which will give you more storage if you don't need or want a huge shower. In the plan(s) further above, with the shower taking up that entire wall, you have *plenty* of room to get out of the shower, towel off and get undressed and dressed. Floor space, a space to hang a towel and lay or hang clothing is all you need - you don't need designated shower-prep-only space.

A knee wall/pony wall would be a good compromise. If you prefer to keep floor to ceiling privacy, frosted glass will allow more light into the space. I think the louvered door to the right in your pic is a linen closet. If it is not or you need more storage, a linen cabinet at the end of the vanity will give the tile a clean end. This is how we decided to end our vanity, provide privacy, and add storage, but we didn't tile our backsplash.

for the size room you have, 25K is barely enough. To stretch that budget you HAVE to DIY some things. Demo will prob save you a few thousand. painting will save you a bit more. Sourcing all your tiles and products and looking for bargains, also saves you. I did this for my own bathroom and saved tens of thousands. But I also played GC for mine. I have a lot of pics with diff ideas. See what you think imagine the tub situated under your window since this window is on the other wall. do a longer vanity, even if a portion of it hits under the window. people like countertop space. Or, between the window and the vanity do an open cubby shelving like shown here, or the next one. unless you have a spot next to your shower for a storage area? then you wouldn't need the tower on the vanity BTW, I love all of these tile/shower designs. this is a 60" vanity w/double sinks, tile wainscot behind the tub. I think you have plenty of room to do a longer vanity w/the free tub in the corner. Ignore the style on this one, but you mentioned a tower. here's one w/single sink and tub under the window. Are you on a raised foundation? becuase if there was someway to move that toilet, it would really help the layout. this bathroom design is pretty close to your layout. you have a longer space on that back wall so your toilet would be between tub/shower. I really like this tile You could basically copy this herringbone on the floor and up the wall, but use larger tiles. (like 4x16 ) Or, you could do a larger hex tile like this black one (or gray or white) and instead of tiling around the tub, do a wainscot/board and batten, like you see here behind this tub. To save money, learn how to DIY this. It's not that difficult. plenty of online tutorials. this is a board/batten. really amps up your space, but would cost you 1-2K to have this done. materials for this can be bought for a few hundred. Do it yourselves (it's mainly math) and save that money for something else. what about something like this? see the board and batten wrapped around the vanity wall to the tub wall? notice the wall mount faucet for the tub? this is a nice, classic look. Then you'd have your toilet, the shower on the other wall. The tile in the shower looks like a 4x16 Shiplap w/a vinyl MDF for damp areas is another option I love this soft blue roman shade too. In this viewpoint, you have the tub with nothing on the wall and a freestanding faucet. Prob your cheaper option. (I really like the first picture I posted. I love the design, the tile work and the items used. Modern Boho. instead of the wainscot , use the white subway tile. However, a tile wainscot will cost more money because of the labor involved) trying to photoshop this tub but the view/angle in the photo is from the other direction. see how it's simple tub w/the wall mount faucet? what if you did that w/it placed on the back wall like shown here in the pic? (look at this view as if you're staning in front of your window. Like the one above w/the Blue vanity. you may have to rotate the one end under the window in order to get the toilet to fit in there. just depends on the size tub you got. you could do a little makeup spot if that countertop takes it under the window. I did find one picture that is almost identical to your layout. (minus the toilet and an extra window) This is a small freestanding tub and would totally work for your room. You could rotate towards the back wall so that you have a longer space on the vanity wall. here's a shower tile option. white subway w/a long niche. source out the tile yourself by shopping around, looking online/craigslist for leftovers you can use. If you buy the shower faucets/hardware individually (example, Kohler Purist on Amazon can save you money if you buy single items at a time) you could save some money. when buying your shower valve, make sure to get it for your specific model shwerhead. if you want the handheld, see if you get a valve that controls both.

I can't get your math from yourdrawing to work at all. But if I have half a guess at your situation, here would be my best suggestion. Close off the closet to the bedroom, open the back of it and build in some storage in the bathroom. Build in a new closet in the bedroom (or get IKEA wardrobe or similar). Put the toilet in front of the window in bathroom, no need to re-size the window. Move the shower. Move the vanity and add storage next to it in the sloped ceiling area. This is going to require redoing your plumbing, but fortunately you still have everything open.