How long has been the rocking going on? If it's more than a few days then it might have become a prop and she is relying on you to go fall asleep. If you think this is the case then I think the only way to tackle this is with PU/PD.
BTW, babies treat day sleep and night sleep a whole lot different so the fact she can ss for naps doesn't mean she knows how to do it for night time sleep.
It also seems that when you give her 3.5h A time in the morning she gives you a better nap than with a 3h A time, which might in fact be too short for her. I'd try and keep the morning A time to 3.5 and keep the day 12h and not more.
On Thursday when you put her at 17:50 to bed she woke up more than 12h later (even if she had NW) and that's great. She probably went into this loop that she goes to bed OT and then has EW. If we can establish the day to be 12h and see that it works then we can start and try slowly to shift her day an hour later. Mind you, it doesn't always work, but one can hope
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