Thanks girls for some great advice. I think having all day morning sickness and "man flu" is making things harder!
I'm trying to remember to be patient with her. The timer is a good idea. We tell her at night she has 5 mins til bed, but I haven't done that during the day with other things. Using an actual timer would be good too as then it's the timer, not me, that's ending whatever it is she is doing!!