End Fortress and End Portal locations reset in game

My friends and I are planning on making a world with 4 end portals (maybe some end portal traps) and we were going to use the original end portal as one of the original 4 end portals. In fact, I used that end portal for the basis of the somewhat X Y Z coordinates of my other end portals. Now I'm facing the issue of, my End Fortress ( you know, the place underground where you find the original end Portal) along with the Town that was above it and everything around it was erased and respawned. I was using the same version I'm using now when I made this and everything... and yet, when I went to look for it once more, it is now gone, it's gone and I found a new underground end fortress... whether or not it has an end portal I do not know, but this does not make me happy as it was much further away than the original end portal was, it is much further away than all the other stuff. The Ender Eye was leading me in the right direction, I know that much, and I teleported to the coordinates, and it was not there, it was all gone. What the heck happened? I checked in on my other End Portal that I had created myself to ensure it was still there, and yes, it is indeed still there. We have not 'finished' the game by defeated the Ender Dragon so there should be no reason for it to have reset if there is a code for it to reset in the new edition. Something glitched or whatever and now I LITERALLY have to make a new end portal in that direction just to match the one I have already made.