Hi Emma,

I went through the same thing when my girl was about the same age; she's 9 months now and really only started sleeping through at about 7 months but every now and then she wakes during the night and only way to get her back to sleep is to BF. I did the top up at night back then with formula thinking if she's full she'll sleep through, arrgghhhh but NO she never did, so I stopped formula feeding at night as a top up as in the end wasn't working and waste of money as we ere never using the tins within the 4 week period that it says on the tin. In the end she just settled and changed herself in her own time and we have gotten use to it that she'll do it when she's ready.
I hope all is going okay for you and it will change, it's just a waiting game.

Emma