Exclusively pumping moms

With my first born, I breast fed more with him then pumping. With my second, I am exclusively pumping due to him tearing my nipples apart and not being able to heal them properly. I am 12 days PP and will usually pump between 1-2.5oz each sessions (every 3-4hrs). I feel like there are days where my boobs have plenty of milk and days my boobs hardly produce any.

What ways helped you increase your supply while pumping? I tried body armour and oatmeal with my first and neither of those did anything.