Oh hon, big hugs. I don't think letting her sleep until nearly 4pm is going to help your BT shenanigans. You know I have a LO who is bordering on hsn if she's bit hsn so i get the fear of the dreaded OT. It is hell (hence my own post today re:R) but it's time to get tough. You need to re-establish your routine, yes? So you will have to cap her nap just to get her to where she need to be at BT so that your whole day/routine can be reestablished. If it were me I would do tbr following:
WU: no later than 8am (if you continue to let her sleep late after being up half the night, she just think, yay I can do that because i get a lay in!)
Nap: 1-3pm ( of she won't nap at 1pm, let her nap later but get her up by 3.30pm to preserve BT)
BT: 7pm
Wash and repeat for 4days to a week and cross everything you've got!
What do you reckon? X