How do I increase more milk to pump

I have to pump I excessively I am getting but as much I expect because my baby is a premie in the NICU so any advice how can I increase naturally my breast milk I’m eating oatmeal spinach uhm water iam drinking recently stopped which I should not and continue to drink more water but is there anything else I can do hes my first and ugh it’s frustrating please help any advice 😞😪