Low amniotic fluid

I’m 34 weeks 6 days and Tuesday I went in for a normal OB app. and had an ultrasound for the first time since 18 weeks. Turns out I had very low amniotic fluid and they admitted me into the hospital to give me fluids and steroid shots just In case I had to deliver early. 48 hours later I had another ultrasound and my fluid had went from 3.8 to 7.3 still under not the best but good enough to go home. Doctor said if I can’t keep it up I will either be back in the hospital till I have the baby or at 37 weeks he will give me a c-section. I feel like just drinking water isn’t enough as I have been home for only a day and my head is killing me because of not getting the same amount of fluid as I was at the hospital. Is there anything I can do, other than drink 2 liters of water a day, to help my amniotic fluid build up fast and stay up?!