Dear Mtmom,
Don't panic. Pump on the medium suction setting for 20-30 minutes at a tme to help to build your milk supply. If you use too high a suction, you can cause tissue damage and damage to the nerve that is responsible for the let-down response. You may not realize the damage is done until it's too late.
Once your baby arrives you can breastfeed with the help of a supplemental nursing system such as a Lact-aid
www.lact-aid.com filled with either donor milk or formula until your own milk supply is well established.
Every drop of your milk is like liquid gold. It's packed with antibodies and other goodies. So even tiny amounts are very important. Breastfeeding is about ever so much more than the milk supply. There is nurturing, bonding, teeth and jaw formation, hand-eye coordination and so on. Bottle feeding moms tend to feed their babies on one side facing away from them so that their babies stare at the bottle instead of mom and they don't switch sides which hinder's hand-eye coordination.
Inducing lactation is a fine thing but once your baby is here, enjoy each and every moment. It's really true that they grow so fast.
Best,