Increase breast milk

My son is 3 weeks old and I’m only able to pump less then 1 oz for both breast. He’s lip tied and has a hard time latching to my breast. He will latch for about 1 minute and cries because he’s hungry. He is currently drinking formula and the small amount of breast milk that I pump. I tried pumping every 2-3 for about 4 days and seen no increase. I’ve tried mother’s tea, body armor drinks, and oatmeal with no increase. I’m slowly giving up. Please help me with tips. I’m afraid I’ll dry up. He is scheduled to have his lip tie fixed next week.