What does it mean when i can feel my bedsheets moving off me during Astral Projection?

ok so when i fall asleep i am still awake and i can't move but wait i know that its called sleep paralysis but i think it may be connected to astral projection because when i was asleep i was in a comfortable meditative trance i was asleep but not with my body i invisioned this place in my head i literally knew i was "asleep" or in a "trance" but i felt like i could get up and move like literally leave my body i was almost there but when i felt my bed sheets move off of me as i was sleeping i got freaked out and broke the trance i was so freaked out by what i was doing i just went back to normal sleep and i knew it wasnt a ghost or a haunting because i did not sense any negative energy around me. I knew i was leaving my body because in my head i saw like a little window to another world but that window was more like a portal opening from dark space. As if i were cutting through time..so i wanna know if its ok that i can feel my bedsheets moving off me as i am in this trance... or better yet i just wanna know if it is safe to completely leave my body and things i should watch out for maybe tonight or any other time of projection. (i guess am asking about the DO's & DONT's of Astral Projection) :) K thanks and if u know some really cool trance songs please feel free to slap'm in there :D thanks lol