Watch some YT vids and break the job into segments.

bathroom floor retiling - YouTube

White tile would be great. Matching trim and toilet etc

Rectangle tile laid horizontal to make room feel wider.

Or smaller white tile laid in a chevon design

https://www.houzz.com/discussions/6620115/tile-for-bathroom-wall

This is a color and style that works well for these two bathrooms. Ignore the funky way that Ai made the shape and placement of the tile.

The reason the tile you have is not working is the dark grout. Choose an epoxy or urethane grout like Mapei for the new tile. Color matched or lighter and your space will feel clean. The builder was too cheap to use it because imported tile guys don't like the time it takes to apply and clean the haze unless they're pros.

The reason to insist on epoxy grout, alight cplpr will not absorb anything and turn darker like cementious grouts. White stays white forever.

Thank you for the advice!

Emily do you have recommendations to what color those tiles are or close too? I actually really like that look