Hi Angie,
You're doing great!! CONGRATULATIONS!!
You might benefit from a visit with an international board certified lactation consultant to see what the story is with your pumping. You can find one here
www.iblce.org Just click on the "About IBLCE" button and the US and International registries appear.
At this point you can try pumping for 20-30 min straight without a break and see if that helps to increase your milk supply. But really, first get hold of an IBCLC to make sure everything is fitting properly. You don't want to damage your breasts before your baby arrives.
Warmest regards,