Depleating Supply?

My baby is ten weeks old, she has PKU so she must have ten ounces of special formula per day, throughout the day and the rest she is breastfed. She starts each feeding with 1-2oz of formula and then nurses immediately after. I’ve been feeling lately like my supply has gotten low in the afternoon/evening time and I’m worried she’s not getting enough. She’s putting on weight just fine- just super fussy and it seems like I’m going dry pretty quickly after she starts to feed.

Is it too late to do something to get my supply back up? What can I do?! I started with sooo much, tooo much- now it’s gone :(