Hi just wanted to say that my son was the same as your dd. He slept on his own, in his own bed and room from 3 mths, no problems. 12 hours solid until 21 months old too. Doing the same thing. Every night the whimpering, its not really a cry but annoying enough to make you get up. Bring him in the bed for an hour while he plays around, back to his bed, hes out like a light. This went on for about 3 months and then I decided to cut his afternoon nap to 2 hours(he was napping 3 or more) and it cut out the night wakings, but he still wakes very early, sometimes 4am for the day. I dont really have any great advice, but I think it is a combo of growing spurts and TV.