How can I get my milk supply back????

Long story short - I planned to breastfeed but had a NICU baby. I pumped around the clock and he was tube fed my milk. I tried every day after he could orally feed to get a latch, but despite constant lactation consultations and a lot of work put into it, he never could latch, so I was stuck with pumping. I continued pumping every 2-3 hours but my supply is down to 1 ounce total output per day which is obviously just a tiny tiny percentage of his total needs.

He is 3 months now and randomly a few days ago he nuzzled me and started latching! He wouldn’t stay on because he got frustrated there was no milk. I tried a few times feeding him some then latching, but he still got frustrated there was no milk. He is interested though and if I had milk I think it’s possible he could breastfeed. If I can continue to get him to latch, can a someone tell me if they know how I can get a milk supply? Is it possible? And to clarify I currently pump around the clock with a properly fitted pump but have no supply. It was so important to me to be able to feed him and it’s been the biggest disappointment. I just want to know if there’s any way to do this before I get my hopes up again. I’ve read a bunch of websites but they all say I should pump to get a supply but I’ve never stopped pumping so maybe my body just can’t make milk anymore?? Also people say just let him latch often but like I said he won’t stay on long without milk there. If anyone has experience or advice I’m open to it!!