Well, with mine, by the stage you are, movement wasn't constant due to there not being so much room in there.
Alex was 8 6, Sam was 8 12.
I was always told by the midwives that if there was no movement for 24 hrs, to go in straight away.
Think about it.....the bigger they are, the less room there is to move around.
What I used to do if I hadn't felt anything for a few hours was to poke & prod them with my fingers to get them to squirm.....lol!