Possible to increase supply at 9 months pp?

FTM to a 9-month-old baby boy, currently mixed feeding. Is it still realistic to increase my supply enough to eventually cut out formula?

We had a rough start to breastfeeding. My baby spent his first 7 days in NICU, and I had a spinal headache from my epidural that lasted over 2 months. Because of that, I wasn’t able to nurse him as much as he needed in those early days, and formula supplementation was introduced from the start.

Since then, I’ve tried just about everything—unlimited latching, pumping, supplements, power pumping, hydration, eating more, you name it. Nothing has made a significant or lasting difference. The only thing that seemed to work was Legendairy Milk supplements. For about a week, I was leaking through my clothes and bedsheets. I’ve also noticed he seems more satisfied when I’m eating a lot more than usual. But even then, he still seems to need formula to be truly full.

Mixed feeding works for us. He’s happy, healthy, thriving, and hitting all his milestones. But I’d still love to increase my supply because he strongly prefers nursing over bottles, and I’d really like to avoid pumping if possible.

The confusing part is that he’s absolutely glued to my breast. Even when he’s clearly hungry, he’ll refuse the bottle and insist on nursing. He’ll stay latched, fussing and crying as if he’s frustrated by the milk flow. But when he finally gives in and takes a bottle or grabs it himself, he drains it so fast it’s obvious he was genuinely hungry all along.

So has anyone successfully increased their milk supply at 9 months pp?