Stay away from those pebble floors unless you have an installer experienced with installing them. Also know that you will have 40% grout vs tile which is the worst thing possible in regards to just about every aspect of installation and upkeep.

They are just a mistake and I would talk to your tile person first. Actually ask your installer about tile sizes. People pick tile by style and sizing should also play a big role. Sometimes certain size tiles just don't work with your rooms layout where simply choosing a smaller size can transform the finished product. You don't want slivers and an odd layout. Be smart and discuss every aspect with the person installing the salesperson is just selling the tile. Make sure associated trim tile are also available. The can't blame you if you discussed prior and have it i writing.

Good luck and some planning will prevent you posting "My tiles are a mess now what", post.

Totally agree with choosing a different flooring for shower. These cannot be done well and create tons of installation issues. It is due in part to how they are being mounted on mesh backing improperly by the manufacturer. Lots of great other choices. Save yourself a lot of headaches. Have you considered a herringbone style tile for flooring and carry right into shower? In a small room this could have a visually expanding look. Have to be planned and laid out really carefully but might be cool. Need at least 2x8" tiles to pull off great look. Best of luck. It already looks like a great little room.

In case you need an alternative... (This is the first I've heard of the pebble install issue.) There is a tile that reminds me of waves and might fit into your beach theme. Included the link below. The store has other shades of blue as well, I just liked that this one has multiple hues.

Arabesque Tile

I would stick to ONE tile for shower walls and floor, ( the lighter as I see pink in vanity top) and IF you are using the sliced pebble on the shower floor, you need a master tiler and perfectly prepared bed . It can be done very successfully, I just used a similar tile for a client in a lake house.. But the tile must be sealed before and after, and you need a MASTERFUL technician, extra tile as well. .....for hand placement of stones in obvious gaps. It's not for the "Chuck in a truck" as one Pro would say.

Personally, I'd consider a change in vanity top, lose the curved back splash, Then look again at all selections. There's a lot of soft gray in that pebble............: ) A remnant solid quartz, can be found for little $$ for a vanity that size, and your shower curb top will require a solid surface in the safest no leak scenario anyway.