I am 22 and I have a 5 year old sister..in the diferent age ranges she was raised pretty much as an only child as well and she sounds just lik eyour little one..I have a suggestion. I don't know how much it will help but i relaly do think it's worth a try at least. Take 1 day and just make it you and her ALL day! NO daddy no friends nobody else just you and her doing what you guys enjoy doing together. If you see that she is NOT acting up with you then you know it's that she wants time with YOU however if she is still acting herself (and even notice either way how she acts the following day) then you need to look at more dicipline if she's still acting that way. I hope it helps but from the sisters percpective I see some things different from my mom and if your daughter is like my sister i'd try it. hope it helps and good luck!!!