37 weeks low amniotic fluid?

Yesterday i went to labor and delivery for a fall and everything was fine. Baby was doing good. But the lady said i have to go back Friday to check my fluid because it was on the low side... Has anyone had this amd what do they do if you have low amniotic fluid? I drink so much water so idk whats going on. I had an ultrasound with my obgyn on feb 4 and he said my fluid was perfect so idk what happened..