L.C.
You have received lots of information about your first question, but not the second. So...
What you can extract from your breasts with a pump is not an indication of how much milk they make --and the volume of milk you make has little to do with its nutritional profile. This means that sometimes a very small amount will have as many calories as a very large amount. Milk composition changes from day to day, throughout the day and throughout a feeding. What your girl gets nursing 'live' will be very different from what she gets from pumped milk.
Most women have a more-productive breast, and many babies have a marked preference for one side, or even one side at one point in the day and the other side at a different point in the day. Just as you have a side that you're more comfortable holding your baby on.
You may like to try manual expression (google 'marmet manual expression technique' and you should find good, illustrated instructions), because many women find it is far more effective at inducing let-down and getting much more milk out and far more comfortable to do.
That said, remember that your baby suckling is part of her immune system: when her mouth contaminates your breast with what she's been exposed to today, your breasts start making germ-specific antibodies for her in your milk before your body starts making those germ-specific antibodies for you.