Milk drying ?

Ti

So my baby is 18 months old I still breastfeed him but my milk seems to be drying up or something he highly depends on it for comfort and bedtime and gets highly upset when nothing comes out is there anything I can do to stop my milk from drying up or somehow increase it when it’s been this long I know I don’t always drink enough water could that be it? I’m stressing because I wanted to wait until he was ready to stop on his own.