Breastfeeding problem! I am trying to exclusively breastfeed but every once in a while my baby acts…

Breastfeeding problem! I am trying to exclusively breastfeed but every once in a while my baby acts like she’s not getting any milk (it’s always in the evening). She is desperate while eating and then unlatches to sob. If I squeeze my boob, I get milk but I don’t know if maybe it’s not enough for her? I hardly get any milk when I pump at this hour bug I’ve heard that it doesn’t determine how much she gets. I am considering supplementing even though I really don’t want to. Help!!