My guess is shes getting too much sleep during the day and isnt tired when it comes to the afternoon. As they get older they dont need as much sleep during the day. Ive always been told to feed them every 3-4 hours turning the day. This means waking them if they are asleep. During the night dont ever wake them though. Ive done this with both kids and both are wonderful sleepers and settle very easily, esp at night. Ive always gone on their lead on how much sleep they want during the day. When they have tired signs i let them sleep. But always wake to feed every 3-4 hours.

So my only suggestion is to not let her sleep so much in the mornings. Get her up give her a feed, let her have a play for an hour or so and continue doing that during the day, so she starts to learn the difference between night and day. How is she sleeping at night? Does she sleep through? If she doesnt, you might find she is having her main sleep during the day, so cutting that down may help her sleep through.

Best of luck.