Hi!
Are you counting 6.30 as EW? An 11.5 hr night might just be her full night's sleep if she has a 7pm BT.
EW can also be linked to start time of a nap, not just the length. So if you want a later wu, you might need to move the start of the first nap later.
Re moving to one nap..it depends on your LO. There isn't a set age to start thr 2-1 transition..this link has info on some signs that a baby might be ready to start capping naps but it is a v gradual process. My DS started showing signs of needing his first nap capped at 10 mo but didn't go consistently to one nap until he was 18mo.
From 2 to 1 nap transition (10-12m and older)Signs of needing to cap a nap further are usually fighting the next nap or fighting BT.
I personally only cap one of the 2 naps to try to avoid OT. It might help to choose one to keep as long as she wants and one to cap.
If she wakes at 7, I'd try to keep her usual amount of first A time & adapt rest of the day around this..depending on whether you choose to cap the first or second nap.
Typical A time at this age is 3-4hrs and can vary through the day.
Exact timings of naps, A times and length of naps are quite a lot of trial and error and it's hard to give you exact answers on these as it depends on your baby. BW is a routine not a timed schedule. Could you observe and record her routine for a few days and see if you see any patterns and come back to chat through what might suit your LO?