Have you tried a later day sleep?
My DD1 transitioned to one sleep aged 13 months (and at that point I wished I'd nudged her thataway sooner, as it was so much easier). DD2 was younger, maybe 11 months, I forget. I always went for an after-lunch day sleep (so around 12.30 or 1pm) rather than a morning one, as we were so often out at various activities during the mornings.
These days, DD2 (now 18 months, has been in this routine for several months now) wakes about 6, has her nap about 12.30 or 1, for a couple of hours, then goes down about 7.30 and sleeps the night (if you call waking every hour for a feed "sleeping", though recently she has made dramatic improvements in that regard).
Seems to me that if your DD is awake from 6.30am to 10am (3.5 hours), then from 12-3 (3 hours), then from 4-7 (3 hours), then it's no wonder she doesn't want to go to sleep at 7. Most babies only need about 12 or 13 hours sleep in total for the day by that age, don't they? I know mine have needed less than that. No way would my kids have slept that early if they had only been awake for 9 or so hours total during the day.
As an aside, things may improve as she becomes more mobile and can tire herself out more physically.
This post has been edited by tenar: 31/01/2013, 08:25 PM