Hi there.
Your LO is very very young and IMO it's hard to tweak when babies are that young, but I will try to help.
IIWY I would do the 5ish nap a CN, so a 45min one, which will bring you, let's say, to 17:45. Then you could have a BT at around 19 and that way not have OT (if that is really the reason for her not settling at BT).
You need to weigh the two things - either leave it like this and you know she sleeps certain hours or have BT earlier and perhaps have a NF (which will be more than normal at that age, even two would be normal). But I can only tell you what I would do, and that would be an earlier BT, because I would like to know that LO is sleeping enough hours at night, rather than having a long stretch.