I need help !!

So i am a first time mom. And im having a lot of trouble balancing taking care of my needs as well as taking care of my daughter. Its hard to eat in the morning with a screaming baby and i haven't been drinking as much water. I take care of her before myself, how do you balance all of this.... my milk supply is down to nada, i cant even feed my child i had to switch to formula full time. I wanted to breast feed till i go back to work if not longer but i cant now..... i need help. How do i keep up milk supply? How do I balance her and my needs plus keeping up everything?? She is onky 3 weeks but im so lost.