As you are unable to get her to bed before 7, could daycare do a slightly later nap? If they could do a 12pm nap and say she slep for 2 hours (hopefully) then a 7pm bedtime would be fine.
How does she fall asleep at bedtime? If she is zonked then I would think that she goes off quite easily, but if she has a slightly later nap you may need to try a little WIWO. If, as Rhian suggests, it is seperation anxiety then you should try Gradual Withdrawl. There is a thread on how to choose which one will suit you and your LO best on the FAQ section on this board.
When I first started sleep training with Alex she was 18 months old and having up to 3 bottles a night and waking for 2-3 hours a night, I was in a right state, but with consistency and the help of members on this board we did it and we haven't looked back. I would say that it about 2 weeks before I saw an improvement, but from then on she sleep so well (My DH, who works away, called it a miracle when he came home from a 3 week stint in Boston)
I hope that this gives you inspiration, it will work, there are ways to help her learn to sleep, you have to show her how it's done.
