I suggest that you try to find some plastic bins that are almost see-through and fit the space. That would be two for each of the lower shelves. You could pull out the bins to see what is inside and even label the outside. Or you could cut your plywood to fit the space and support it on the built-in shelves with bricks or purchased legs. The problem with this is that things in the back would be even more hidden than they are now. Then for the upper left you might be able to find a set of shelves that would fit. For the top right, I would put big soft things that you can grab and that won't hurt you when they hit you on the head! This might be extra bedding, towels, out-of-season clothes. For children's clothing I like to fold the whole outfit together, so that one doesn't have to hunt for the "matching" part. I think that your cosmetics could be in a small box that fits on top of other bins or clothing on shelves. Good luck. This will take some experimenting, but something will emerge.

It's a bit hard to tell, it looks like some of the proportions are not correct. Given what you have drawn it looks like entering and exiting your shower is going to be awkward. I'm not certain that you'll be able to open the door all the way because of the placement of the tub and vanity. Here are a few suggestions: Ditch the corner tub, and use a rectangular one that is installed with the long end on the wall opposite the vanity and shower and install the toilet next to the tub. Slide the door to the right, and you'll be able to have a larger vanity and/or shower. If you can use a pocket door or something of the like you'll gain wall space like sandpat mentioned. I don't see any storage planned. Have you thought about where you'll keep towels, toiletries, etc-?

I think this piece is quite lovely. It appears that your couch and chairs have dark wood so I would be tempted to stain or paint the buffet to match these items. Changing the large modern handles to smaller antique ones might help to make it less bulky looking and tie in with the other items in your room.. I like the idea of putting a mirror in the upper door, however much as I like the criss cross effect in the sample pictures, adding more detail may conflict with the curves in your sofa and chairs. You could look for a decorative detail that has more subtle style. As for placement, it might go on the short wall where you have a bench or even on the wall where you have your table with two chairs, one on each side to balance the look.

The red brick wall as a backdrop sounds very interesting. You can get quirky posters of various liquor brands like Jack Daniels, Chivas etc in black and white and get it framed and put them on the wall. Also industrial look is very in so the bar top can be done using a copper sheet over a plywood top instead of traditional granite or marble. Also utilise any empty beer bottles or wine bottles to make a customised chandelier. For stools you could have wrought iron stools with leather seats matching the brick wall. A small wall shelf with a display of shot glasses will make the look more interesting. Hope this is helpful, it will be great if you can share pictures of the area to give some more inputs.