Hi Yvonna,
I pumped from the time my baby was 6 weeks old because I went back to work, and just stopped completely this past week. My son will be 1 on the 20th, so take it from someone who pumped a lot b/c my son would barely nurse at all once I went back to work...Your output can vary a lot. Mine varied greatly just depending on what time of day I was pumping. Also, about the time I was ovulating until my period started, my supply would go way down. Then after my period the supply would go back up for about 1/2 month, then ovulation would hit again. Have you recently started your period back or do you suspect that you are about to?
Have you tried messaging your breast while you are pumping, or at the least take breaks from pumping, then start back again. When I pumped I would push and squeeze (gently of course) every drop I could get out of my breast. Many times you can find what I call pressue points in your breast...that when you push in certain places, the milk comes out faster. Also, fenugreek, alfalfa, and mothers milk plus did help me to pump more. Eventually I had to use Reglan because my supply really did drop dramatically.
My other suggestion is that maybe your breast are just getting used to the pump. Are you all the way up on suction and speed? If you are, you may have to use another pump for a little while. I had three...Medelas Pump in Style, the Playtex Embrace, and the Medela Swing. I would rotate between them to try and ward off my breast getting used to them. Maybe you have a friend who has a different pump you can borrow or switch for a couple of weeks?
Hopefully any of this will help.