Hi, it's not totally uncommon for an EBF baby to still have two NFs at this age, but I can understand you working at getting rid of one. It is true that introducing a DF at this age can disrupt their sleep cycles and cause more NWs, but I think there's no harm in trying it. Then, you at least are getting to sleep more (not having to wake shortly after you to to bed) and ideally if you continue to bring the feed earlier, that should be an easier way to drop it. If, after a week or so, her night sleep seems more disrupted by the DF than helped, then I would just try to drop that feed by resettling her when she wakes. She won't like it much the first few times, but you know she's capable of making it longer, so you can be confident in resettling.
I always feed her at 4:30am as there is no way she will go back to sleep otherwise and I can't start my day then!!!
I think this signals that your routine still needs to be tweaked a bit. You've done a great job at getting her this far from constant 45min naps, but she still seems to be caught in a UT/OT type cycle. Her morning A time is quite low for her age (and I'm sure she's tired as she has a short pm nap and is likely OT by BT. But, it's a bit of a catch-22 in that she gets that nice restorative nap, but then the cycle starts anew with a short pm nap and likely OT at BT again. At 7.5mo, the average A time is 3hr-3hr15min. I'd start pushing the morning nap back by 10-15min every few days until you get close to 3hr. She then should be able to go another 3ish hr (maybe until 15:30 again) and hopefully take a decent second nap as the day will be a bit more even and she'll be the right amount of tired for it. A more age-appropriate routine should help better night sleep follow.
A couple questions just to be sure...
Is she an independent sleeper at naps and BT (goes into her crib awake and settles herself)?
How is her solids intake? You've got her down for 3 meals, does she eat well at them or little bits still?