Well, we went out yesterday (pre and post nap), and things were much better. For most of the morning, I was a bit reserved with her (not sulking!)and held back on initiating cuddles and telling her I love her. Thought I'd stand back, and let her come to me. And she did. Got lots of "I love you mummy", and in general, my adorable dd had returned.
In the afternoon, she was very good while I spoke on the phone to an old friend in the USA for quite a long while. After the call she said "mummy I was good and let you talk on the phone" - so she is trying to be good, bless her!
We had some minor incidents last night that could have escalated, but I didn't allow them to. For some bizarre reason, she thinks it is funny to try to spit her saliva - where she got that from, heaven knows! I keep telling her that it isn't a nice thing to do, but she persists - almost daring me to take action. Last night as we were cuddling before bed, she did it. I told her to stop, but she continued. I ignored her, and she kept doing it with increasing vigor. Finally I simply said "That's not nice and mummy doesn't like it. If you keep doing it, we'll have a problem. I would much rather sit here and have a nice time with you before bed, so please stop". And she did, thankfully.
Tigermoth and sobernow - I have faith in our nanny, and don't think she is undermining me. She's actually very firm with dd, and has been teaching me (!) to be the same if I want better behavior. I think what is more likely to be happening is dd is playing one off the other. I am a single mum, so dd doesn't have the option of saying "I want daddy" when things aren't to her liking. Recently she has started saying "I want (nanny) to be my mummy", but in the past she has also said "I want (my good friend) to be my mummy." So, I tend to think it is more playing one off the other - just in our case, the other is a non-family member. And yes sobernow, those comments seem to come when I'm being strict with her and she's not getting to do exactly as she likes.
So, here's hoping for a better week. It's my birthday today, so the best present she could give me is a happy, loving day free of conflict. And thanks again to all of you for your support and kind words.