You need to gently stimulate the baby continuously while feeding either by rubbing sole or near ear so that she doesn't sleep off early without filling of stomach.
Check if baby is latching correctly or not.
Even after good latch and feeding if baby remains hungry then your milk may not be sufficient.
If that is the case use tab. Lactare 2 tablets three times daily.
Health Tips
Take foods which increase milk production like garlic, jeera, oats, bread, methi, barley,almonds.