Thanks for all the advice ladies!
I did take a blanket off last night because I was worried about her overheating with the fever so might put it back on tonight. I might use the under arm one during the day - I like the ear one at night because I dont have to wake her - although when I went in a 2am (set my alarm!!) she was awake and then I had to feed her after she smiled at me and I tried to sneak back out! No chance! Normally she will go through for 11 hours - she obviously does wake but falls back asleep again!