Hi there,
I wonder if maybe she's sleeping too much during the day. Could you try maybe to add a little A to her day and shorten her daytime sleep to 3 hrs so its something like this:
7am - wake
10-11.30 - morning nap
2.30-4 - afternoon nap
7pm - bedtime
Try adding 15mins every couple of days so that her A is around 3hrs (which is about the average for a 7mo).
What is she like when she wakes? Do you help her get back to sleep or she just awake and chatting? Have you started solids yet? Do you think she may be in some sort of discomfort?