Hi there
Looks like you've been at this for about a month now is that right? And LO is about 8 months old?
I would suggest doing set naps for a number of days to get her into a new routine, after that you can adapt based on usual cues such as an extra stimulating day might need a slightly earlier nap or BT etc, but to get into a good routine Tracy often watched the clock and kept LO up for long periods without worrying about OT. This could well be your quickest solution to implementing a routine you will all find more predictable.
I'd suggest:
WU any, the aim is 6.30/7am
A 3.5hr (until WU moves to 7am this A time will be longer, that's fine)
S 10.30 - 12.00 (stay close to help resettle if an OT nap comes)
A 3hr
S 3.00 - 4.30
A 3hr
BT 7.30
Over night 11 (or possibly 11.5) and do not expect more.
If you read some of Tracy's interviews or examples in her books, she suggested using any method needed to keep LO awake to establish a good routine, she said do a fan dance if necessary. So that first nap is coming considerably later than your LO is used to and you might need to deploy the fan dance to get through. It might even be that for a couple of days you find it impossible to get her through to 10.30, and nap might end up being 10 or 10.15 but the thing is to do your best to get there. You might be tempted to move nap 2 much earlier if nap 1 is short, This isn't how Tracy established routine, she kept LO up until the very close to the next nap time, and also woke them at WU time if they were so tired they wanted to sleep longer. Usually on the forums we go slower and more gently (partly because it is quite hard work on parents) but IMO when you've been trying gently for over a month it's probably time to grit your teeth and make this happen.
As Kelly said, when you got the later WU you put her down for a nap much earlier than needed, got a short nap, short day and back to square one with the early BT and earlier than you want WU the next morning. My suggestion on routine means sticking pretty close to it for several days. Your LO may well become OT, Tracy was never scared of that, it means in the end they sleep and get on a suitable routine. It's harder but it's quicker and it works. Be there if your LO has OT WUs or NWs and help her settle.
My absolute worst times have been when DS was UT and I didn't shift the sleep times late enough.
Hope this helps
Good luck.