Last night, I tried twice, back to back to do astral projection. I was using a guided meditation on YouTube which got me much farther in the process than it did purely on my thoughts. The experiences I'm about to explain are the same for both times albeit the first time it took a while to feel a particular sensation which I will explain. I was relaxed, in my thoughts. However, I could feel my physical body swallowing (a natural reaction) since I was laying down. But I was relaxed nonetheless. I felt vibrations on my arms. It was like this for minutes. I did what the guide in the video said to do. The sensation: suddenly, I felt my heart pound and I literally felt like I was floating. I could feel my heart beat incredibly fast, I knew I was sweating a little, and I could hear my heart beat. The second time it seems like I visualized my room (my TV, PS4) but I have no idea if it was just all in my head or if I was really seeing this. Was I astral projecting? If yes, why did I return to my physical body? If no, what was I doing wrong? Even though my attempts were futile, I felt very relaxed thereafter, relieved more or less.
Welcome to the Pulse!
What you are describing are pretty common early exit sensations, so whatever you are doing is apparently working insofar as getting you to this point. The key is to stay calm and work your way through the sensations and this may take several tries. The rapid heart feeling will calm down with a few more experiences. Try working in some floating or swaying side to side feelings and just release and go with it.
Check out some of the dark blue sticky topics at the top of the first and third boards. There is some really good information in those.