Having trouble positioning my map art in Minecraft

The map does not center on the player when created, rather, the world is broken up into large invisible grid squares, and the map displays the area of whichever grid square it is in when it is first used. For example, if a player uses a new map in a certain grid square, and then moves a distance away and uses another fresh map but is still within the same grid square, both maps appear identical. To make a map that is not identical to the first one, the player would have to move outside of the edges of the first map (because then they would be in a new grid square). This way, no two maps can ever partially overlap and every map can display only a fixed area.

Unfortunately, there is no option other than moving your pixel art to a grid square. Open an empty map and go to the corner of it and start the pixel art from there and make sure it is within the map.