K.K.
Hello there - I too exclusively breast feed my son who is now 6 months. There have been moments where I too have panicked because he has emptied both breasts and was still hungry! Some things to keep in mind is that your body responds to your baby better than it does the pump and your milk production is based on supply& demand. If your little on starts eating more your body will produce more.
When my son was 2 months I started working out which unbenounced to me affected my milk supply. My Pediatrician recommended doubling my fluid intake and also recommended Fenugreek (an OTC herbal supplement that helps increase production). Keeping my fluid intake up and taking the Fenugreek helped significantly. When I started pumping I would get around 2 oz out of each side. Now that my son eats more and I have a pumping routine at work I pump 4 oz on each side 3 times a day. You'll get there - it just takes a little bit of time so be patient - Ultimately, your body knows and will react to your babies needs! Good luck ;)