Penny, Have a look at the out side of your house, to see if the gutter is straight, there should be a slight fall to the down pipe 1cm per 1m or 1" in(normal), look at the windows, are they in line "the ones upstairs" then look at the ones down stairs, they should also be in line. When you are in the bathroom can you see any cracks in the wall or in the tile work.( look at all the walls inside) As Henry in Mi said, some times the floor will run away to one end to take water away from the center. when carpenters hang doors they should leave a space around the door of about 3mm or 1/8" not more. Look at the lock in the bathroom door, it should close with ease against the look keep and door jamb. "if the lock does not fit well, or not at all then there is something wrong, very wrong." If every thing is OK, the get a carpenter ( not the one who hung the door in the first place) get him to fit an extra strip of timber ON THE BOTTOM OF THE DOOR then plane the door to fit.