Reset when entering own world

Then something wrong when entering my worlds. When entering my world I spawn a completely different space then I left. Instead I spawn the place I left before that, with the things I had in my inventory then. And in two of my world I have even spawned at spawn point and nothing in my inventory, like I had never been in that world before, even trough I clearly had. It is really annoying because then I lose valueable things in my inventory, and have to go a long way to get where I left of. Pls fix.