Joshua a Hart

I'm having the same issue, I lost so much stuff and its maki g finding a nether fortress impossible 

The original overworld portal puts me at the original nether portal, or after a hoglin  came though it put me at a second  portal in the nether,  which drops you 20 blocks above a lava sea on one side and soild rock the other.

If you reenter portal 2, it takes you to over world portal 2 which is 2600ish blocks away on the x axis and 70 above the never ending sea , that leads you to portal 3 nether which is 2600 blocks into the nether,  re enter that I get dropped at overworld portal 3 in a swamp 16000 blocks away.  Re enter that I go to the nether 16000 blocks away from zero. Here there's no portal visible. Also my bubble meter starts and stops.  But if I stand where I am spawned I return to overworld.

Overworld 255 72 95

First nether 29 74 11

Second nether 260 45 110

Currently I will enter overworld 1, go to nether portal 2,  walk to nether portal one and return to overworld 1.

But...I found out that portal facing matters.  If I enter east facing it will reverse the process listed, west entry will make it bigger and bigger jumps

And now to get weirder, Later in the day I went to my furnace and pulled my iron when I put the iron in my inventory, the mushrooms popped out on the floor. 

All missing 28 of them. 

They also were not in my inventory earlier, and it was full and emptied several times between the disappearance and reappearance a day later.