Hi and welcome to BW
Wow your situation sounds exhausting!
Could you expand a little so we can get a fuller picture of what's happening?
When you were working nights and her BT routine went off track what did her sleep routine end up looking like? (when was BT and WU and naps if any?)
Now you are working days and she is up all night can you show what her current sleep routine looks like? so she doesn't go to sleep until 3,4 or 5am but when do you begin your wind down and BT routine? What do you do between wind down and when she actually falls to sleep if she is awake for so long?
What time does she WU after going to sleep at that time?
You say no naps but does she fall asleep if you go out in the car etc or nod off at meals or watching TV etc?
What sort of activities happen in the day, for instance are you able to get outside into the sun, go to parks for play etc? Are the 3 children with a childminder in the day whilst you work? Do you know the routine?
Does she eat her meals at regular times, with the rest of the family?
Sorry for so many questions but it would help us to come up with some ideas for you if we have a bit more information.
Meanwhile - hang in there, I'm sure we can come up with a plan to help you resolve this and get more sleep for the whole family.