Low supply and hungry baby

My babe just hit one month the 21st and we had a rough start to breast feeding with him being in nicu, and I tested positive for covid so I couldn’t see him at all while he was there..

He latches on fine (per lactation specialist) and eating every 2-3 hours but isn’t gaining weight fast enough.

He has plenty of wet and soiled diapers and seems content MOST of the time.

My concern is when I pump I’m getting less than a ounce every time!

I use my haakaa when nursing and that’s how I’ve been able to build my little supply but I don’t know what else to do😩😩