My three were all sleeping through at that age and were formula fed too. Their last feed was at 7.30pm - 8pm and then they'd sleep through until 7am (lucky me!). By 6mths though they were having solid feeds aswell. Sometimes they would wake and just be content and if they did this i'd let them go until they'd self settle back to sleep. But if they didn't I'd usually give them a bottle to get them back to sleep. Even adults will wake through the night and not go straight back to sleep, so I'd say that yeah, she does sleep through. It's frustrating sometimes when you don't know if you should feed them to settle them or let them go. If she is content just to lay there, I'd leave her alone and she will go back to sleep soon enough (so long as you are happy letting her stay awake like this). Hope this helps you a bit.