R3 is the room below R2. Look at the preview at the site. Theres two hanger thingies. And chairs. Thats shown in the room below R2. (I think)
I thought that R3 was below it as well, but it just didn't make sense for how we'd travel around to get there according to the map. Like we'd have to go all the way across to the other end of the map after that room to get to the tattoo parlor and then the gallery is the huge area in the middle. There's no other rooms in that lower portion that could be the tattoo parlor so I just based it around travelling in one set direction the whole way so it's not zigzagging around everywhere. The lower room to the left is obviously the shell with the huge square tub (?) on the map so I just made the lower part number 7 so it lead back to the bedroom for R8.