Unexpected teleportation with the nether portal

My portal which is at coordinates 950/60/150 approximately took me to an absolutely new area in the nether and when I came back it took me to the overworld at coordinates 7488/64/1104 (as seen in the image) . as soon as I appeared in the nether I immediately realized that something was wrong having found myself in an area unknown to me (it was not the first time I entered the nether on my world.