@Rosie Longstreeth , it's all a bit of a puzzle, will maybe get back with a few thoughts on it later on, but, meantime, if you're using libre regularly, there's a small transmitter called "blucon nightrider" which you can buy for £96 from
www.ambrosiasys.com as a one-off cost, put it on top of your sensor with a plaster, link it to an android app called xDrip+ and it'll automatically read the sensor every 5 mins, so it'll give you hypo alerts.
Obviously, that doesn't address the underlying issue, but it'll at least mean that while you figure out ways of sorting it out, you'll at least have the security blanket of getting woken up by the phone ringing if you drop too low instead of getting repeated hypos night after night, which must be sooo tiring.
You can set the hypo alarm to any level you want, so, say you set it to 6 or 7, it'll catch you on the sharp drop down from the teens, and give you time to figure out how much carb you need to tail it off so it stops about 5.5 instead of going into hypo-land and not rebounding too much.
It'll maybe give you a bit of respite while you get the larger issues sorted out.