Hi!
You seem to have done an OBE, which is also known as astral projection. It is a subset of WILDing. I managed to do it once, and it was rather fulfilling. People often feel bizarre sensations like pressure, buzzing, vibrating and random stuff like that just before they 'exit'. All I can say is don't stress about the enormous pressure, and it will only get worse with thinking about it excessively.