Every time I enter the end portal (the one that is activated when you kill the dragon) for return to the normal world it appears to me that I have died and I lose all my things.

I was in the final dimension getting some blocks and I got tired so I wanted to go back to the normal world and when I went through the portal on the screen it seemed to me that I had died because I fell from a high place, and I lost all my experience, I tried to see where my things were, but in the end I did not they were nowhere.
I thought it was a simple mistake and they would fix it after I left and re-entered the world, but I still couldn't find my stuff.
So I went back at the end to take out the blocks and when I wanted to return to the normal world through the portal it seemed to me that I had died and again I lost everything, I felt very worried because I had lost many things, so I made a copy of my world and in the copy I tried to enter the final portal to see if the same thing appeared to me but every time I tried to return it seemed that I had Ddad and my things were not there, it was practically that I was trapped in the dimension of the end and when I tried to leave I died And I lost everything, technically the only way to escape was to die.
I felt really bad since I had spent a lot of time in that world and I also needed to get to the end because I had an enderman farm in that dimension.
Hope it can be solved. I have devoted a lot of time and patience to the world and I don't want to lose it.
I hope you understand me and thank you very much for reading.