Minecraft : nether portals issues [duplicate]

I had a normal portal system before, but today I decided to get ontop of the nether (the bedrock) and build a better\more organized portal system when I did it, I just moved the portals exactly on the top (I didn't change the X OR Z coordinators) just the Y.

So I got in the portal from the nether and it linked with the one at my base (home), that's great, but when I came back to the nether it didn't link with the one on top, it generated a new one, I broke the new one and tried again, and it's still not working.

Any ideas about how to figure it out? Besides than going back to the old system (not on top)

edit:it's not a duplicated question and that's why: I'm not in the ordinary nether I'm on top of the bedrock and i know that each nether block is 8 blocks in the over world and my portal is in the exact same location of the over world multiplied by 8 in the nether

From the wiki on nether portal:

Starting at these destination coordinates, the game looks for the closest active portal. It searches a bounding area of 128 horizontal blocks from the player, and the full map height (128 for the Nether, 256 for the Overworld). This gives a search area of 257 blocks by 257 blocks, at the full height of the dimension being traveled to.

Unfortunately, the game never searches above the map height so it will never find your portal on the nether roof.

You can build a portal on top of the nether which you can enter and will exit to the overworld. There is no way to enter a portal in the overworld and exit from a portal on top of the nether.

Sadly you cannot keep a functional portal on top of the Nether. I have tried this myself