Low supply

Megan

My son is 2 +3 weeks and I was only pumping 2 or 3 times a day and getting 2-3 ounces each time so up to 9 ounce + plus breast feeding a day but he started having a hard time latching so I am pumping every 3 hrs I only get up to .5 ounce from both breast total. So only at most 4 ounces a day.. I’ve been exclusively pumping for 3 days now

What can I do to increase supply