Don't panic - maybe your daughter doesn't need the amount of sleep that some other babies do? She seems to sleep a very long night, going from 7pm til 7 or 8 the following morning - so maybe she needs stimulation during her waking hours, instead of being fed and expected to go down again for a bit. From 12 weeks old, I set aside an afternoon playtime, which included gentle sitting exercises. My eldest son was walking at eight and a half months, and he was as bright as a button. I spent time reading to both children, even before they could understand a word, and pointing out colours and numbers & playing with toys that made sounds or moved. It might work for you - x.