how do you know its time to leave work and Stay at home with your kids?

we are in a bind at the moment.

financially we are not better off me being at work as we have to fork out over $400 a week in day care for 2 kids.

i only just cover this with my income.

i am feeling guilty being at work when i just want to stay home and keep the great Bf'ing journey going. it looked like it was over but it all came back

i feel guilty when i only work half a day as i dont feel it is worthwhile.

i love my job though and feel guilty for thinking of leaving or dropping back to just one day.

i am torn.
just wondering how you overcome this and make the right decision

as if i pull the girls out i may not get the days back and wont be able to work.
but if i keep working will i regret it later on.