Two kids and so financially stressed

I have a 2.5 month old and a 2 year old and my goodness I'm so financially stressed. I was paid per diem so I go no maternitt leave. Im going to have to go back to work asap. I dont REALLY mind but i also know its going to take me a while to get paid again. I have like 300 left in my account (my portion is 700) and rent is due tomorrow. My fiance is helping with whatever he can and is paying our shared bills but i cant pay my own. Anyone have advice or been in this situation?