Up your milk supply?

Brooklynn • 23, married, mom to 2 wonderful boys, Mason and Tristan, and a 3rd boy is due July 9th, 2020.
How did you other mommy's increase your milk supply? I'm pumping right now because my baby has a tongue tie and can't latch. I'm only getting about 4-5 ounces about every 6 hours. What do I do? I don't want to stop breastfeeding yet but if I run dry I have no choice :(