M.P.
even with normal periods I find if I sit more than 30 minutes, in a certain way, when I get up I GUSH... when I laying down on my back almost flat I gush. I have a tipped Uterus, and was told that blood likes to pool there. After my 3 kids it was like yours. Light to almost none some days, and then others it was like I was shot. Though nothing came of it for me. I literally was sharing my kids diapers as a pad cause it was so heavy some days. I had no choice but to be active after all of them cause I was alone the majority of the time with 2 of my 3.