So it seems as though she should go down then really

.
If you think there might be a correlation with dropping the night feed then she might have extended - have you tried 8.25ish?
I think TBH you might need to just keep doing as you are doing and see if this one rides itself out. It seems as though it is like wakeful evenings but in reverse - and they just tend to eventually settle. All you can do if offer sleep at sleepy times - and if she will not settle then use AP if you think she is entering OT land.
As the rest of your day is good at least you get a clean sheet every morning to try something new.
Thinking back I remember having so much trouble with my DS starting around the same time. There is a bit of developmental thing that happens around now where they start to experience light sleep and drifting off - whereas as newborns it is all crash out into a coma

. This is the age where the short napping can start as well I'm afraid. First they sort out their night sleep (which your DD seems to have done VERY well) and then they start to arrange their day sleep. I remember my Dad taking 6 weeks to even see my DS with his eyes open, but by 8 weeks he was taking 4 catnaps a day. I wasn't BWing properly then but I'm not sure much of it was preventable - I think it was developmental.
Try a slightly longer A 'just to check', and if not I would just keep offering sleep on her cues. Try for 20 mins or so to help her to sleep and if she doesn't them get her up - see how she is - and AP the nap if you need to.
At this age if you are achieving independent crib sleep for one nap a day you are doing really well so I wouldn't worry to much if you end up using AP every now and again to avoid OT. I think most of us continue to work like that even when they get much older - as long as the majority of their sleep is independent and you KNOW they have the skills and have no true props then it really doesn't matter.
Hope I am making sense here.