Do you all think she is still looking after a year and a half? Or are the finer details lost on you?

You could always see if someone you know is looking for 2 full days and that way you could offer full time work without having to up your pay. Even if the nanny had the others kids on an overlapping day it could work. In these p/t situations its good to think outside the box

You could also think about adding five hours a week - I did this with a family where we planned out the schedule a month in advance. Sometimes I worked a half weekday, other times it was for a date night, but it brought me up to 35 hours which was close enough to FT for me.