All our kitties sleep in various rooms each night but one cat, Stinky has always slept with us. It works out well for the most part when she stays at the foot of the bed but lately she has been sleeping right in the crook of my knees when I'm laying on my side. I guess it's warmer but it drives me crazy and I have the worst sleep because I don't want to disturb her but it's pretty uncomfortable for me. I think I'm going to get her furry soft circular bed and put it at the foot of the bed and encourage her to sleep in it. She's actually pretty good about going to her 'area' when we say "down to your bed, off you go..." After staring at us like we are being incredibly rude to ask such a thing, she wanders to the end of the bed and settles in. Lately I've been letting her have her way but I need my sleep so tonight we go back to the old routine. We can all share the bed but we have our sections.
Maybe it would help you if you had a bed for her that you could tuck off to the side towards the bottom? That way you could stretch out freely and get a good sleep.