Help-Low Supply-4 weeks PP

Help... baby was 4 weeks early and had lost 10% at first pediatrician appt. They recommended supplementing an ounce per feed while still BF, which we did. A week later we did a weighted feed with the LC and he didn’t gain a gram after 20 mins of feeding. He is a very sleepy feeder. LC suggested alternating between pumping and BF, which I did for a week. He is slowly gaining and was back up past birth weight just last week (8 pounds 9oz). Did second weighted feed with LC last week and still did gain anything during that feed. She then suggested to pump exclusively. With power pumping once a day and pumping very 2-3 hours I am still only producing 1 oz max. Sometimes I’ll only get 20 mL. I can see my supply has increased from 4 oz I a day to nearly 8. Introduced lactation cookies and supplements, drinking tons of water... but starting to feel like my supply is never going to catch up. I dread pumping as it hurts and is so discouraging to only get 10 mL after 20 mins. Took a break and just breastfed today (with formula supplement) but wonder if he even got anything. Feeling like I will never catch up as he is eating 2.5-3 oz per feed of formula

(every 2-3 hours). Any advice appreciated!