[Freddy]

One possible thought: don't prioritize worrying about whether you're in the right position, that will come. Rather, make it a priority to immediately identify the area you are to cover from the position you arrive at. Do this by quickly tracing the boundaries of that area with your eyes when you arrive at that position, then observe the play in that area both on-ball when in that area but especially off-ball when the ball is in your partners' area.
Do that every time you arrive at any of the three typical positions, T, C, or L. Do that every time you rotate.
Think "area to cover" first and foremost, not "Where am I supposed to be?"
This will help you make the calls you need to make in your area. The rotation mechanics will come over time. Probably quicker than you think.
Hope this makes sense. Others' valuable insights will likely assist you better. Check out their advise and put it all together.
But this is the slight mind-shift that helped me get over the hump that lies before you.